HVAC scrubber unit operational control systems and methods

ABSTRACT

Systems and methods for improving operation of a heating, ventilation, and air conditioning system, which includes a scrubber unit coupled to an air handling unit via a return air conduit. The scrubber unit includes a contaminant filter, which sorbs air contaminants from a surrounding environment when at a target pressure differential and releases previously sorbed air contaminants into the surrounding environment when at target temperature, a return inlet actuator coupled to a return inlet damper, and scrubber control circuitry programmed to determine parameters of outside air and instruct the return inlet actuator to ramp the return inlet damper from a closed position to an open position during a bleed phase of a regeneration cycle to enable venting of the previously sorbed air contaminants using return air when the parameters of the outside air are not within corresponding target parameter ranges.

CROSS-REFERENCE TO RELATED APPLICATIONS

This a Non-Provisional application claiming priority to and benefit ofU.S. Provisional Application No. 62/523,132, entitled “CONTAMINANTSCRUBBER OF AN HVAC SYSTEM” and filed Jun. 21, 2017, which is hereinincorporated by reference in its entirety for all purposes.

BACKGROUND

The present disclosure generally relates to heating, ventilation, andair conditioning (HVAC) systems and, more particularly, to scrubberunits that may be implemented in an HVAC system.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present techniques,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Generally, an HVAC system may operate to provide temperature controlledair to an internal space, for example, in a building. In particular, theHVAC system may adjust temperature of supply air provided to theinternal space based on a temperature setpoint (e.g., target temperatureof supply air), for example, via one or more heat exchangers. As supplyair is provided, the HVAC system may receive return air from theinternal space, for example, to facilitate maintaining air pressurewithin the internal space relatively constant.

However, in some instances, return air may include a contaminants, suchas carbon dioxide, formaldehyde, and/or other volatile organiccompounds. For example, carbon dioxide level (e.g., parts per billion)in return air may be higher than carbon dioxide level in outside air dueto higher concentration of living beings (e.g., humans and/or animals)and, thus, breathing in the internal space. When contaminant level inreturn air is higher than a target contaminant level of supply air, theHVAC system may generate supply air provided to the internal space bycombining return air with outside air. However, since temperature ofreturn air is generally closer to target temperature of supply air, theHVAC system, at least in some instances, may adjust temperature ofreturn air more efficiently than temperature of outside air.

SUMMARY

Certain embodiments commensurate in scope with the disclosed subjectmatter are summarized below. These embodiments are not intended to limitthe scope of the disclosure, but rather these embodiments are intendedonly to provide a brief summary of certain disclosed embodiments.Indeed, the present disclosure may encompass a variety of forms that maybe similar to or different from the embodiments set forth below.

In one embodiment, a heating, ventilation, and air conditioning systemincludes an air handling unit that provides temperature controlledsupply air to an internal space and a scrubber unit fluidly coupled tothe air handling unit via a return air conduit. The scrubber unitincludes a contaminant filter, which sorbs air contaminants from asurrounding environment when at a first target temperature and a targetpressure differential and releases previously sorbed air contaminantsinto the surrounding environment when at a second target temperaturehigher than the first target temperature, a return inlet actuatormechanically coupled to a return inlet damper, in which the return inletdamper is fluidly coupled between the contaminant filter and the returnair conduit, and scrubber control circuitry communicatively coupled tothe return inlet actuator, in which the scrubber control circuitry isprogrammed to determine parameters of outside air and instruct thereturn inlet actuator to ramp the return inlet damper from a fullyclosed position to an open position during a bleed phase of aregeneration cycle to enable venting of the previously sorbed aircontaminants using return air when the parameters of the outside air arenot within corresponding target parameter ranges.

In another embodiment, a method for operating a scrubber unitimplemented in heating, ventilation, and air conditioning systemincludes determining, using one or more processors, parameters ofoutside air fluidly coupled to the scrubber unit via an outside airconduit and determining, using the one or more processors, filteringefficiency of a contaminant filter implemented in the scrubber unitbased at least in part on an input contaminant level indicated by areturn inlet sensor and an output contaminant level indicated by areturn outlet sensor. When the filtering efficiency of the contaminantfilter is below an efficiency threshold, the method includesinstructing, using the one or more processors, a return inlet actuatorto maintain a return inlet damper fluidly coupled between thecontaminant filter and a return air conduit in a fully closed positionduring a first duration; instructing, using the one or more processors,an outside inlet actuator to maintain an outside inlet damper fluidlycoupled between the contaminant filter and the outside air conduit inthe fully closed position during the first duration; and instructing,using the one or more processors, one of the return inlet actuator andthe outside inlet actuator to ramp a corresponding inlet damper from thefully closed position to an open position based at least in part on theparameters of the outside air during a second duration after the firstduration.

In another embodiment, a scrubber unit to be implemented in a heating,ventilation, and air conditioning system includes a first internalsegment implemented between a first cross-member and a secondcross-member, in which the first internal segment includes a contaminantfilter; a second internal segment implemented between the secondcross-member and a bottom panel of the scrubber unit, in which thesecond internal segment includes a fan and a heater implemented betweenthe fan and the contaminant filter; a third internal segment implementedbetween the first cross-member and a top panel of the scrubber unit, inwhich the third internal segment includes a closed loop damper fluidlycoupled between an outlet damper coupled to the top panel of thescrubber unit and an inlet damper coupled to a sidewall of the scrubberunit; and a control panel coupled to the sidewall of the scrubber unit,in which the control panel comprises control circuitry is programmed todetermine filtering efficiency of the contaminant filter based at leastin part on input contaminant level measured at the inlet damper andoutput contaminant level measured at the outlet damper; and instruct thescrubber unit to operate in a regeneration mode when the filteringefficiency of the contaminant filter falls below an efficiency thresholdto facilitate improving the filtering efficiency available duringsubsequent operation of the scrubber unit.

DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a perspective view of a building including a heating,ventilating, and air conditioning (HVAC) subsystem, in accordance withan aspect of the present disclosure;

FIG. 2 is a block diagram of a portion of the building of FIG. 1including a building management system (BMS) and various buildingsubsystems, in accordance with an aspect of the present disclosure;

FIG. 3 is schematic diagram of an example of the HVAC subsystem of FIG.1 including an air handling unit (AHU) and a scrubber unit, inaccordance with an aspect of the present disclosure;

FIG. 4 is a schematic diagram of an example of the scrubber unit of FIG.3 including a control panel, in accordance with an aspect of the presentdisclosure;

FIG. 5 is a block diagram of an example of the control panel of FIG. 4including scrubber control circuitry, in accordance with an aspect ofthe present disclosure;

FIG. 6 is a flow diagram of a process for operating the scrubber controlcircuitry of FIG. 5, in accordance with an aspect of the presentdisclosure;

FIG. 7 is a flow diagram of a process for controlling operation of thescrubber unit of FIG. 4, in accordance with an aspect of the presentdisclosure;

FIG. 8 is a flow diagram of a process for operating the scrubber unit ofFIG. 4 in a standby mode, in accordance with an aspect of the presentdisclosure;

FIG. 9 is a flow diagram of a process for operating the scrubber unit ofFIG. 4 in a sorption mode, in accordance with an aspect of the presentdisclosure;

FIG. 10 is a flow diagram of a process for operating the scrubber unitof FIG. 4 in a regeneration mode, in accordance with an aspect of thepresent disclosure;

FIG. 11 is a flow diagram of a process for operating the scrubber unitof FIG. 4 in a closed loop heating phase of the regeneration mode, inaccordance with an aspect of the present disclosure;

FIG. 12 is a flow diagram of a process for operating the scrubber unitof FIG. 4 in a bleed phase of the regeneration mode, in accordance withan aspect of the present disclosure;

FIG. 13 is a flow diagram of a process for operating the scrubber unitof FIG. 4 in a cool down phase of the regeneration mode, in accordancewith an aspect of the present disclosure;

FIG. 14 is a flow diagram of a process for operating the scrubber unitof FIG. 4 in one of multiple regeneration modes, in accordance with anaspect of the present disclosure;

FIG. 15 is a flow diagram of a process for monitoring operation of thescrubber unit of FIG. 4, in accordance with an aspect of the presentdisclosure;

FIG. 16 is a flow diagram of a process for controlling operation of theair handling unit (AHU) of FIG. 3 when the scrubber unit of FIG. 4 is inthe standby mode or the regeneration mode, in accordance with an aspectof the present disclosure;

FIG. 17 is a flow diagram of a process for controlling operation of theair handling unit (AHU) of FIG. 3 when the scrubber unit of FIG. 4 is inthe sorption mode, in accordance with an aspect of the presentdisclosure;

FIG. 18 is an example of a graphical user interface (GUI) generated bythe building management system of FIG. 2, in accordance with an aspectof the present disclosure;

FIG. 19 is another example of a graphical user interface (GUI) generatedby the building management system of FIG. 2, in accordance with anaspect of the present disclosure;

FIG. 20 is an overhead perspective view of the scrubber unit of FIG. 4,in accordance with an aspect of the present disclosure;

FIG. 21 is a close-up, overhead, perspective view of a cross-memberimplemented in the scrubber unit of FIG. 20, in accordance with anaspect of the present disclosure;

FIG. 22 is a front view of a set of filter cartridges implemented in thescrubber unit of FIG. 20, in accordance with an aspect of the presentdisclosure;

FIG. 23 is an overhead perspective view of a door system implemented onthe scrubber unit of FIG. 20, in accordance with an aspect of thepresent disclosure;

FIG. 24 is a close-up side view of a door included in the door system ofFIG. 23, in accordance with an aspect of the present disclosure;

FIG. 25 is an exploded perspective view of a fan system implemented inthe scrubber unit of FIG. 20, in accordance with an aspect of thepresent disclosure;

FIG. 26 is an overhead perspective view of a control box implemented onthe scrubber unit of FIG. 20, in accordance with an aspect of thepresent disclosure;

FIG. 27 is an overhead perspective view of a top panel implemented onthe scrubber unit of FIG. 20, in accordance with an aspect of thepresent disclosure;

FIG. 28 is a close-up, exploded, perspective view of an eyelet lifterimplemented on the top panel of FIG. 27, taken along line 13-13 in FIG.12, in accordance with an aspect of the present disclosure;

FIG. 29 is an overhead perspective view of an air damper implemented onthe scrubber unit of FIG. 20, in accordance with an aspect of thepresent disclosure;

FIG. 30 is a close-up, exploded, perspective view of a mounting bracketimplemented to secure an actuator to the air damper of FIG. 29, inaccordance with an aspect of the present disclosure;

FIG. 31 is an overhead perspective view of the air damper of FIG. 29installed in a panel of the scrubber unit of FIG. 20, in accordance withan aspect of the present disclosure;

FIG. 32 is a close-up, exploded, perspective view of a spin ringimplemented in the panel of FIG. 31, in accordance with an aspect of thepresent disclosure;

FIG. 33 is an overhead perspective view of a bottom panel implemented onthe scrubber unit of FIG. 20, in accordance with an aspect of thepresent disclosure; and

FIG. 34 is a close-up, exploded, perspective view of a foot mountingassembly implemented on the bottom panel of FIG. 33, in accordance withan aspect of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. These described embodiments are only examples of thepresently disclosed techniques. Additionally, in an effort to provide aconcise description of these embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but may nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

Often, a building includes one or more building subsystems, such as aheating, ventilation, and air conditioning (HVAC) subsystem thatsupplies temperature controlled air to an internal space within thebuilding. To facilitate producing temperature controlled air, the HVACsubsystem may include an air handling unit (AHU) that operates to adjusttemperature of supply air based on a temperature setpoint (e.g., targettemperature) associated with the internal space. For example, when airflows over (e.g., around) a heat exchanger coil in the air handling unitwhile fluid (e.g., water or refrigerant) is being circulated through theair handling unit, the heat exchanger coil may facilitate heat transferbetween the fluid and the air, thereby changing temperature of the air.Thus, to facilitate controlling temperature, the air handling unit maycontrol flow rate of supply air over the heat exchanger coil and/or flowrate of fluid circulated through the air handling unit.

As supply air is provided to an internal space, the HVAC subsystem mayreceive (e.g., draw) return air from the internal space, for example, tofacilitate maintaining air pressure within the internal space relativelyconstant. Since supply air is provided to the internal space,temperature of return air from the internal space may generally be closeto the target temperature of the supply air. Thus, to facilitateimproving operational efficiency, the air handling unit may producesupply air to be subsequently provided to the internal space using atleast a portion of the return air.

However, in some instances, return air may include air contaminants,such as carbon dioxide, formaldehyde, and/or other volatile organiccompounds (VOCs). For example, carbon dioxide level (e.g., parts perbillion) in return air may be higher than carbon dioxide level inoutside air due to higher concentration of living beings (e.g., humansand/or animals) and, thus, breathing in the internal space. Whencontaminant level in return air is higher than a target contaminantlevel of supply air, the air handling unit may generate the supply airby combining the return air with outside air. However, when differencebetween outside air temperature and the temperature setpoint is greaterthan difference between return air temperature and the temperaturesetpoint, operation of the air handling unit may less efficiently adjusttemperature of supply air produced using a combination of return air andoutside air, for example, compared to supply air produced using onlyreturn air. In other words, at least in some instances, amount ofoutside air used to produce supply air may affect operational efficiencyof the air handling unit and, thus, the HVAC subsystem.

To facilitate improving operational efficiency, the present disclosureprovides techniques for implementing and/or controlling operation of oneor more scrubber units in an HVAC system (e.g., subsystem integratedwith a building management system). As will be described in more detailbelow, in some embodiments, a scrubber unit may be fluidly coupled toone or more air handling units to facilitate reducing contaminant levelpresent in return air, for example, when operating in a sorption mode.Additionally, in some embodiments, an internal portion of a scrubberunit may include a closed loop damper, a contaminant filter, a heater,and a fan. In particular, the heater may increase temperature of airwithin the internal portion of the scrubber unit when turned on, damperposition of the closed loop damper may limit re-circulation of airwithin the internal portion of the scrubber unit, and the fan may force(e.g., push or pull) air through the contaminant filter when turned on.Additionally, in some embodiments, the contaminant filter may includechemical compounds that sorb (e.g., absorb or adsorb) contaminants fromits surrounding environment while undergoing a first chemical reactionand that release previously sorbed contaminants into its surroundingenvironment while undergoing a second chemical reaction.

The scrubber unit may also include an outside inlet damper and anoutside outlet damper fluidly coupled between its internal portion andone or more outside air conduits (e.g., ducts). In other words, damperposition of the outside inlet damper may limit flow of outside air intothe internal portion of the scrubber unit and damper position of theoutside outlet damper may limit flow of air out from the internalportion of the scrubber unit to an outside air conduit. Additionally,the scrubber unit may include a return inlet damper and a return outletdamper fluidly coupled between the internal portion and one or morereturn air conduits (e.g., ducts). In other words, damper position ofthe return inlet damper may limit flow of return air into the internalportion of the scrubber unit and damper position of the return outletdamper may limit flow of air out from the internal portion of thescrubber unit to a return air conduit. For example, return air may flowthrough the internal portion of the scrubber unit when the return inletdamper and the return outlet damper are both in at least partially openpositions.

To facilitate improving operational efficiency, as described above, theHVAC subsystem may be implemented such that one or more scrubber unitsare fluidly coupled to one or more air handling units. For example, anair handling unit may be fluidly coupled to the return air conduit alongwith the scrubber unit. To facilitate producing supply air, the airhandling unit may also be fluidly coupled to an outside air conduit.

In some embodiments, the air handling unit may include a return airdamper fluidly coupled between the return air conduit and an internalportion, which includes one or more heat exchanger coils. In otherwords, damper position of the return air damper may limit flow of returnair into the internal portion of the air handling unit. Additionally,the air handling unit may include an outside air damper fluidly coupledbetween the outside air conduit and the internal portion of the airhandling unit. In other words, damper position of the outside air dampermay limit flow of outside air into the internal portion of the airhandling unit. Thus, in some embodiments, the air handling unit mayproduce supply air using only return air, only outside air, or acombination of return air and outside air, for example, by controllingdamper position of the return air damper and/or damper position of theoutside air damper.

To facilitate reducing amount of outside air used in supply air, in someembodiments, a scrubber unit may operate in a sorption mode to sorb(e.g., trap) contaminants present in return air flowing through thescrubber unit. As described above, in some embodiments, a contaminantfilter in the scrubber unit may sorb contaminants while the chemicalcompounds in its one or more filter cartridges undergo a first chemicalreaction and release previously sorbed contaminants into its surroundingenvironment while the chemical compounds in its one or more filtercartridges undergo a second chemical reaction. In some embodiments, thesecond chemical reaction may occur when temperature of the contaminantfilter is elevated, for example, above a temperature threshold.Additionally, in some embodiments, the first chemical reaction may occurwhen pressure differential across the contaminant filter is elevated,for example, above a pressure differential threshold.

Thus, while operating in the sorption mode, the scrubber unit mayactively introduce a pressure differential across its contaminantfilter, for example, by modulating speed of its fan based at least inpart on a target sorption pressure differential. In some embodiments,the target sorption pressure differential may be determined based atleast in part on the pressure differential threshold, for example, suchthat the target sorption pressure differential includes a range ofpressure differentials at or above the pressure differential threshold.To facilitate sorbing air contaminants, in some embodiments, thescrubber unit may maintain temperature of its contaminant filter at atarget sorption temperature, for example, which includes a range oftemperatures at or below the temperature threshold by maintaining itsheater off. Thus, when return air flows through scrubber unit whileoperating in the sorption mode, the scrubber unit may facilitatereducing contaminant level in the return air, which at least in someinstances may facilitate improving operational efficiency of the airhandling unit, for example, by enabling the supply air to be producedusing less outside air.

In some embodiments, filtering efficiency of a contaminant filter maychange over time. For example, as amount of sorbed air contaminantsincreases, filtering efficiency of the contaminant filter may graduallydecrease. Thus, in some embodiments, the filtering efficiency may bedetermined and tracked. For example, filter efficiency may be determinedbased at least in part on input air contaminant level determined by areturn inlet sensor coupled on the return inlet damper and output aircontaminant level determined via a return outlet sensor coupled on thereturn outlet damper.

To facilitate improving filtering efficiency during subsequentoperation, in some embodiments, a scrubber unit may operate in aregeneration mode to release and vent (e.g., exhaust) previously sorbedair contaminants from its contaminant filter. For example, the scrubberunit may operate in a quick regeneration mode when filtering efficiencyof its contaminant filter is reduced below a filtering efficiencythreshold. Additionally or alternatively, the scrubber unit mayperiodically operate in a regeneration mode based at least in part oncurrent and/or expected (e.g., future) occupancy of the building. Forexample, the scrubber unit operate in an extended regeneration mode whenthe building is expected to be unoccupied a duration greater than aduration threshold and a standard regeneration mode when the building isexpected to be unoccupied a duration not greater than the durationthreshold. In any case, a regeneration mode may generally include aclosed loop heating phase, a bleed phase, and a cool down phase.

While in the closed loop heating phase, a scrubber unit may operate toincrease temperature of its contaminant filter from a previous targetoperating (e.g., sorption or standby) temperature, for example, bypulsing the heater on and off based at least in part on a targetregeneration temperature (e.g., 145° Fahrenheit). As described above, insome embodiments, a contaminant filter may release previously sorbedcontaminants into its surrounding environment while chemical compoundsin its one or more filter cartridges undergo a second chemical reaction,for example, due to its temperature being elevated above the temperaturethreshold. Thus, in such embodiments, the target regenerationtemperature may be determined based at least in part on the temperaturethreshold, for example, such that the target regeneration temperatureincludes a range of temperatures at or above the temperature threshold.By operating in this manner, the scrubber unit may begin releasingpreviously sorbed air contaminants from its contaminant filter duringthe closed loop heating phase.

Subsequently, the scrubber unit may operate in the bleed phase toexhaust (e.g., vent) released air contaminants from the HVAC subsystem,for example, by at least partially opening the outside outlet damper toenable the released air contaminants to flow from the internal portionof the scrubber unit to an outside air duct. To facilitate increasingamount of air contaminants released from its contaminant filter during aregeneration cycle, in some embodiments, the scrubber unit may continuecontrolling temperature of its contaminant filter based at least in parton the target regeneration temperature, thereby enabling the contaminantfilter to continue releasing previously sorbed air contaminants duringthe bleed phase. Since temperature of outside air may differ from thetarget regeneration temperature, the scrubber unit, in such embodiments,may gradually exhaust released air contaminants during the bleed phase,for example, by gradually ramping the outside air damper from a closedposition toward an open position to facilitate increasing amount ofcontaminants removed from the contaminant filter during a regenerationcycle.

As described above, in some embodiments, a contaminant filter may sorbcontaminants from its surrounding environment while the chemicalcompounds in its one or more filter cartridges undergo a first chemicalreaction, for example, due to pressure differential across thecontaminant filter being elevated above the pressure differentialthreshold while its temperature is below the temperature threshold. Inother words, to facilitate sorbing air contaminants during subsequentoperation, temperature of the contaminant filter may be reduced belowthe temperature threshold, for example, based at least in part on asubsequent target operating (e.g., sorption or standby) temperature thatincludes a range of temperatures at or below the temperature threshold.Since contaminant filter temperature may be elevated during the closedloop heating phase and the bleed phase, a scrubber unit may operate inthe cool down phase to facilitate reducing temperature of itscontaminant filter, for example, by maintaining the heater off andmaintaining the fan on. By operating in this manner, temperature of thecontaminant filter may be reduced during the cool down phase, which atleast in some instances may facilitate reducing duration before thescrubber unit is subsequently able to operate in the sorption mode.

In any case, by operating in a (e.g., quick, standard, or extended)regeneration mode, a scrubber unit may release previously sorbed aircontaminants from its contaminant filter during a regeneration cycle,which at least in some instances may facilitate improving filteringefficiency provided by the contaminant filter during subsequentoperation. As described above, in some embodiments, filtering efficiencyof a contaminant filter may be determined based at least in part oninput air contaminant level and/or output air contaminant level, forexample, indicated by sensor data output from the return inlet sensorand/or the return outlet sensor of a scrubber unit. Additionally oralternatively, the return inlet sensor and/or the return outlet sensormay output sensor data indicative of other return air parameters, suchas temperature and/or humidity of the return air flowing through thescrubber unit.

In some embodiments, operation of other portions of an HVAC subsystemmay be controlled based at least in part on return air parameters. Forexample, contaminant level present in return air may be used to controlamount of outside air used by an air handling unit to produce supply airin accordance with the target contaminant level. Additionally oralternatively, temperature of return air may be used to control amountof temperature adjustment provided by the air handling unit to producesupply air in accordance with a temperature setpoint. However,implementing sensors in an HVAC subsystem may affect implementationassociated cost, such as component count in the HVAC subsystem,manufacturing steps used to implement the HVAC subsystem, and/or size(e.g., physical footprint) of the HVAC subsystem.

To facilitate reducing implementation associated cost, in someembodiments, a scrubber unit may operate in a standby mode to enableflow of return air through the scrubber unit without activelyintroducing a pressure differential across its contaminant filter, forexample, by at least partially opening its return inlet damper and itsreturn outlet damper while maintaining its fan off. In other words, thescrubber unit may operate to facilitate determination of return airparameters even when the contaminant filter is not actively sorbing aircontaminants. In this manner, by operating in the standby mode, thescrubber unit may facilitate reducing implementation associated cost ofthe HVAC subsystem, for example, by obviating implementation ofadditional sensors for determination of return air parameters.

To facilitate switching between the various operational modes, in someembodiments, a scrubber unit may include scrubber (e.g., dedicated)control circuitry, for example, implemented in a control panel coupledto a housing of the scrubber unit. In some embodiments, the scrubbercontrol circuitry may be communicatively coupled to sensors implementedin the scrubber unit, for example, to enable the scrubber controlcircuitry to monitor operation of the scrubber unit and/or parameters ofair (e.g., outside air and/or return air) flowing through the scrubberunit based at least in part on sensor data received from the sensors.Additionally, the scrubber control circuitry may be communicativelycoupled to equipment implemented in the scrubber unit, such as a fanmotor, a switching device in a fan relay module, a switching device in aheater relay module, and/or an actuator mechanically coupled to an airdamper in the scrubber unit. In this manner, the scrubber controlcircuitry may control operation of the scrubber unit by communicatingcontrol commands that instruct equipment in the scrubber unit to adjustoperation.

In addition to controlling operation of the scrubber unit, in someembodiments, the scrubber control circuitry may control operation ofother portions of the HVAC subsystem. For example, the scrubber controlcircuitry may instruct an actuator external from the scrubber unit toadjust damper position of an outside air damper implemented in an airhandling unit based at least in part on a target outside air damperposition. In some embodiments, the scrubber control circuitry maydetermine the target outside air damper position based at least in parton operational status of the air handling unit and/or parameters ofoutside air. To facilitate determining operational status of the airhandling unit, in some embodiments, the scrubber control circuitry maybe communicatively coupled to air handler (e.g., dedicated) controlcircuitry, for example, to enable the scrubber control circuitry todetermine whether the air handling unit is on or off based at least inpart on status data received from the air handler control circuitry. Tofacilitate determining outside air parameters, in some embodiments, thescrubber control circuitry may be communicatively coupled to one or moresensors external from the scrubber unit, for example, implemented on theoutside air damper to enable the scrubber control circuitry to determinetemperature, humidity, and/or contaminant level of outside air based atleast in part on sensor data received from an external sensor. In thismanner, the scrubber control circuitry may facilitate controlling and/ormonitoring operation of an HVAC subsystem implemented to providetemperature controlled air to an internal space within a building.

As described above, in some embodiments, a building may include multiplebuilding subsystems. For example, in addition to an HVAC subsystem, thebuilding may include a lighting subsystem, an electrical subsystem, asecurity subsystem, and/or a water subsystem. In some embodiments,controlling operation of one building subsystem based at least in parton operation of another building subsystem may facilitate improvingoperational efficiency, for example, by reducing power consumption(e.g., usage) attributed to operation of the building subsystems.

As an illustrative example, occupancy status of a building may bedetermined based at least in part on video captured by an image sensor(e.g., camera) in a security subsystem. By controlling operation basedat least in part on the occupancy status, an HVAC subsystem mayadaptively (e.g., dynamically) adjust temperature setpoint for supplyair. For example, when the occupancy status indicates that a buildingzone is unoccupied, the HVAC subsystem may adjust temperature setpointsuch that less cooling is applied to supply air provided to thatbuilding zone. Additionally or alternatively, since each providesdiffering tradeoffs between duration a scrubber unit is unavailable tooperate in the sorption mode and filtering efficiency provided duringsubsequent operation, the scrubber control circuitry may instruct thescrubber unit to operate in one of the quick regeneration mode, thestandard regeneration mode, and the extended regeneration mode based atleast in part on current occupancy and/or expected future occupancy ofthe building. In this manner, at least in some instances, coordinatingoperation of multiple building subsystems may facilitate improvingoperation of one or more of the multiple building subsystems.

In some embodiments, a building management system may be implemented tofacilitate coordinating operation of multiple building subsystems. Forexample, the building management system may receive image datacorresponding with video captured by the security system. By analyzingthe image data, the building management system may determine a currentoccupancy status of the building and communicate occupancy (e.g., state)data indicative of the current occupancy status to the HVAC subsystem.In some embodiments, based at least in part on the occupancy data, theHVAC subsystem may determine whether the building is currently occupied,whether a building zone in the building is currently occupied, number ofindividuals currently occupying the building, number of individualscurrently occupying the building zone, and/or location of individualscurrently occupying the building. For example, when it determines thatthe building is currently occupied and filtering efficiency is below thefiltering efficiency threshold, the scrubber control circuitry mayinstruct the scrubber unit to operate in the quick regeneration mode.

Additionally, in some embodiments, the building management system maydetermine expected future occupancy status of the building, for example,by predicting the future occupancy based at least in part on previous(e.g., historical) occupancy of the building. Based at least in part onoccupancy data indicative of the expected future occupancy status, insome embodiments, the HVAC subsystem may determine when the building isexpected to be unoccupied and/or duration before the building isexpected to be occupied. For example, when it determines that thebuilding is currently unoccupied and expected to remain unoccupied aduration greater than a duration threshold, the scrubber controlcircuitry may instruct the scrubber unit to operate in the extendedregeneration mode. Additionally, when it determines that the building iscurrently unoccupied and that the duration the building is expected toremain unoccupied is not greater than the duration threshold, thescrubber control circuitry may instruct the scrubber to operate in thestandard regeneration mode.

In some embodiments, to facilitate coordinating operation of multiplebuilding subsystems, a building management system may generate andsupply a supervisor clock signal to one or more of the buildingsubsystems. For example, the building management system may instruct thesecurity subsystem and/or the HVAC subsystem to operate using thesupervisor clock signal. Nevertheless, in some embodiments, a buildingsubsystem may generate an internal clock signal to facilitate improvingimplementation flexibility, for example, by enabling the buildingsubsystem to be deployed as a standalone system. Thus, when deployed inan integrated system, the building management system may override theinternal clock signal by instructing the building subsystem to insteadoperate using the supervisor clock signal. In other words, in someembodiments, scrubber control circuitry may selectively operate usingits internal clock signal or a supervisor clock signal based at least inpart on whether the HVAC subsystem is integrated with a buildingmanagement system.

Moreover, in some embodiments, a building management system mayfacilitate controlling operation of a building subsystem based at leastin part on information provided by a remote data source. For example,the building management system may retrieve weather information (e.g.,data) from a remote data source, such as a database server or theinternet. To facilitate controlling operation of an outside air damperof an air handling unit, the building management system may analyze theweather information to determine parameters of the outside air, such astemperature, humidity, and/or contaminant level. By communicatingparameter (e.g., state) data indicative of the outside air parameters,the building management system may enable the scrubber control circuitryto determine suitability of outside air for use in supply air and/or forventing air contaminants released during a regeneration mode. In anycase, by implementing and/or controlling operation of one or morescrubber units in this manner, the techniques described in the presentdisclosure may facilitate improving operational efficiency of an HVACsystem (e.g., subsystem) and, thus, a building in which the HVAC systemis implemented.

To help illustrate, an example of a building 10 including an HVACsubsystem 12 is shown in FIG. 1. It should be appreciated, that thedepicted building 10 is merely intended by illustrative and notlimiting. For example, the building 10 may be a commercial structure ora residential structure. Additionally or alternatively, the building 10may include other subsystems, such as a lighting subsystem, anelectrical subsystem, a security subsystem, and/or a water subsystem.

In any case, in the depicted example, the HVAC subsystem 12 includes anair side 16 and a fluid side 14, which may circulate fluid (e.g., water,glycol, or refrigerant) through the air side 16. For example, the fluidside 14 may supply temperature controlled fluid to the air side 16 viaone or more supply fluid pipes 18 (e.g., conduits) and receive fluidreturning from the air side 16 via one or more return fluid pipes 20(e.g., conduits). To facilitate producing heated fluid, the fluid side14 may include one or more boilers 22 that operate to add heat to thecirculated fluid, for example, by burning combustible material (e.g.,natural gas) or using an electric heating element. To facilitateproducing cooled fluid, the fluid side 14 may include one or morechillers 24 that operate to remove heat from the circulated fluid, forexample, by placing the circulated fluid in a heat exchange relationshipwith another fluid (e.g., refrigerant).

Additionally, in some embodiments, the air side 16 may circulate airthrough internal portions of the building 10. For example, the air side16 may supply temperature controlled air to an internal space within thebuilding 10 via one or more supply air ducts 26 (e.g., conduits) andreceive return air from the internal space via one or more return airducts 28 (e.g., conduits). To facilitate producing temperaturecontrolled supply air, the air side 16 may include one or more airhandling units (AHUs) 30 that adjust temperature of supply air, forexample, by placing the supply air in a heat exchange relationship withthe fluid received from the fluid side 14.

In some embodiments, an air handling unit 30 may produce supply airusing any combination of air returned from an internal portion of thebuilding 10 and air drawn from outside (e.g., external) the building 10.In other words, the air handling unit 30 may produce supply air usingonly return air, only outside air, or both return air and outside air.Additionally, in some embodiments, an air handling unit 30 may adjusttemperature of supply air to be supplied to an internal portion of thebuilding 10 based at least in part on an associated temperaturesetpoint, for example, set via a thermostat and/or user inputs receivedfrom a client device.

To facilitate providing more granular temperature control, in someembodiments, the internal portion of the building 10 may be divided intomultiple building zones each associated with its own at least relativelyindependently adjustable temperature setpoint. For example, the building10 may be divided such that each floor is identified as a differentbuilding zone. To facilitate varying supply air provided to differentbuilding zones, in some embodiments, the air side 16 may include one ormore variable air volume (VAV) units 32 coupled on the supply air ducts26 and/or the return air ducts 28. For example, a variable air volumeunit 32 on each floor may control amount of supply air provided to itscorresponding building zone. Thus, in some embodiments, a variable airvolume unit 32 may include one or more air dampers and/or other flowcontrol elements.

In any case, the HVAC subsystem 12 may operate to control parameters(e.g., flow rate, temperature, contaminant level, and/or humidity) ofsupply air provided to each building zone in the building 10. Asdescribed above, in some embodiments, a building 10 may include multiplebuilding subsystems. In other words, in addition to an HVAC subsystem12, the building 10 may include other subsystems, such as a lightingsubsystem, an electrical subsystem, a security subsystem, and/or a watersubsystem. Since operation of different building subsystems may affectone another, in some embodiments, a building management system (BMS) maycoordinate operation of the various building subsystems implemented in acorresponding building 10 or group of buildings 10 (e.g., campus).

To help illustrate, an example of a building management system 34implemented to coordinate operation of multiple buildingsubsystems—namely an HVAC subsystem 12, a lighting subsystem 36, anelectrical subsystem 38, a security subsystem 40, and a water subsystem42—is shown in FIG. 2. It should be appreciated that the depictedembodiment is merely intended to be illustrative and not limiting. Forexample, in other embodiments, the building management system 34 mayadditionally or alternatively be integrated with other subsystems, suchas a refrigeration subsystem, an advertising or signage subsystem, acooking subsystem, a vending subsystem, a lift/escalators subsystem, afire safety subsystem, an information communication technology (ICT)subsystem, and/or a printer or copy service subsystem.

To facilitate coordinating operation of multiple building subsystems,the building management system 34 may include a processor 44, memory 46,and one or more communication interfaces 48, for example, that operatein accordance with a supervisor clock signal. In some embodiments, acommunication interface 48 may communicatively couple the buildingmanagement system 34 to a communication network 62, such as a personalarea network (PAN), a local area network (LAN), and/or a wide areanetwork (WAN). For example, a first communication interface 48 maycommunicatively couple the building management system 34 to each of thebuilding subsystems via a first communication network 62A, therebyenabling data communication between the building management system 34and the various building subsystems. Additionally, a secondcommunication interface 48 may communicatively couple the buildingmanagement system 34 to one or more client devices 64 and/or to one ormore remote data sources 66 via a second communication network 62B.

In some embodiments, the memory 46 may include one or more tangible,non-transitory, computer-readable media that store instructionsexecutable by the processor 44 and/or data to be processed by theprocessor 44. For example, the memory 46 may include random accessmemory (RAM), read only memory (ROM), flash memory, hard drives, opticaldiscs, and/or the like. Additionally, the processor 44 may include oneor more general purpose microprocessors, one or more applicationspecific processors (ASICs), one or more field programmable logic arrays(FPGAs), or any combination thereof.

In any case, by executing corresponding instructions, the buildingmanagement system 34 may perform various operations (e.g., functions).In some embodiments, the building management system 34 may performoperations based on a supervisor clock signal, for example, generated bythe building management system 34 and supplied to one or more buildingsubsystems to facilitate coordinating operation with the buildingmanagement system 34 and/or with one another. Additionally, in someembodiments, the operations may be organized into multiple hierarchallayers (e.g., applications). For example, the memory 46 may storeinstructions corresponding with an enterprise integration layer 50, ameasurement and validation layer 52, a demand response layer 54, a faultdetection and diagnostics layer 56, an integrated control layer 58, anda subsystem integration layer 60.

Generally, the building management system 34 may provide operationalcontrol across multiple building subsystem via the integrated controllayer 58. For example, by executing instructions corresponding with theintegrated control layer 58, the building management system 34 maydetermine a control strategy (e.g., one or more control actions) to beimplemented by one or more of the building subsystems over a controlhorizon (e.g., period of time). In some embodiments, the buildingmanagement system 34 may determine a control strategy based at least inpart on operational parameters of the building subsystems, for example,indicated by sensor data output from a sensor and/or state datadetermined based at least in part on the sensor data. Additionally, insome embodiments, the building management system 34 may determine acontrol strategy based at least in part on information received from aremote data source 66, such as a weather server that communicatesweather data indicative of environmental conditions (e.g., temperature,atmospheric pressure, contaminant level, and/or humidity of outside air)to the building management system 34. Furthermore, in some embodiments,the building management system 34 may determine a control strategy basedat least in part on user (e.g., operator) commands, for example,received via input devices 68 on a client device 64.

In addition to receiving user commands, in some embodiments, a clientdevice 64 may facilitate communicating information to a user, forexample, by displaying a visual representation of building subsystemoperational parameters and/or a visual representation of a determinedcontrol strategy. To implement a determined control strategy, thebuilding management system 34 may communicate at least correspondingportions of the control strategy to the building subsystems. In otherwords, the building management system 34 may communicate on a subsystemlevel with each of the various building subsystems and on an enterpriselevel with an enterprise application, for example, running on a clientdevice 64 and/or a remote data source 66.

Often, electronic devices communicate data using one of any number ofcommunication protocols, which often are not directly compatible. Forexample, control modules manufactured by a first vendor may communicateusing one (e.g., BACnet) communication protocol while control modulesmanufactured by a second vendor communicate using a different (e.g.,Modbus) communication protocol. Thus, to facilitate improvingoperational flexibility, the subsystem integration layer 60 mayintegrate data communication between the building management system 34and the building subsystems, for example, by converting communicationprotocol used to indicate received sensor data (e.g., signals) and/oroutput control commands (e.g., signals). Additionally, the enterpriseintegration layer 50 may integrate data communication between thebuilding management system 34 and enterprise applications, for example,by generating a graphical user interface that includes a visualrepresentation of a building subsystem operational parameter and/orconverting communication protocol used to indicate input (e.g., user orremote) data. A more detailed description of the various layers that maybe implemented in a building management system 34 can be found incommonly assigned U.S. Pat. No. 8,600,556, which is incorporated hereinby reference in its entirety for all purposes.

In any case, by operating in this manner, a building management system34 may facilitate coordinating operation of multiple building subsystemsby enabling operation of one building subsystem to be controlled basedat least in part on information determined outside that buildingsubsystem, for example, by a different building subsystem and/or by aremote data source 66. As an illustrative example, when a buildingemployee badges in at a parking garage, the security subsystem 40 mayindicate occurrence of the event to the building management system 34.Based on indication of the event, the building management system 34 maydetermine a control strategy in which the lighting subsystem 36 turns onthe lights in the building employee's office, the electrical system 38boots up the building employee's computer, and/or the HVAC subsystem 12begins cooling the building employee's office.

In other words, as in the above example, a security subsystem 40 mayfacilitate determining occupancy status (e.g., current occupancy) of acorresponding building 10. To facilitate determining occupancy status,in some embodiments, a security system 40 may include one or more videosurveillance cameras that each captures a visual representation (e.g.,video) of its proximate surroundings as image data. Additionally oralternatively, the security subsystem 40 may include other equipment thefacilitates determining occupancy (e.g., state) data indicative ofoccupancy status, such as occupancy sensors, digital video recorders,video processing servers, intrusion detection devices, access controldevices, motion sensors, and/or the like.

At least in some instances, controlling operation of a buildingsubsystem based at least in part on building occupancy may facilitateimproving operational efficiency, for example, by reducing powerconsumption resulting from its operation. As an illustrative example,when occupancy data is indicative of the building 10 being 20% occupied,the building management system 34 may determine a control strategy inwhich the electrical subsystem 38 disconnects electrical power from 80%of the elevators in the building 10, thereby facilitating a reduction inpower consumption. Additionally, when occupancy data is indicative of abuilding zone being unoccupied, the building management system 34 maydetermine a control strategy that adjusts target temperature and/ortarget flow rate of supply air provided by the HVAC subsystem 12 to theunoccupied building zone.

To implement its corresponding portion of a control strategy, controlcircuitry may control operation of equipment in the HVAC subsystem 12.For example, the control circuitry may control operation of an airhandling unit 30 to adjust temperature of the supply air. Additionally,the control circuitry may control position of one or more air dampers,for example, to adjust amount of return air used to produce the supplyair. As described above, contaminant level is often the limiting factoron amount of return air that may be used in supply air. Thus, tofacilitate increasing amount of return air used to produce supply air,the control circuitry may control operation of one or more scrubberunits 70 to sorb (e.g., absorb or adsorb) air contaminants from thereturn air, which at least in some instances may facilitate improvingoperational efficiency of the HVAC subsystem 12.

To help illustrate, an example of a portion 72 (e.g., air side 16) of anHVAC subsystem 12 including an air handling unit 30 and a scrubber unit70 is shown in FIG. 3. It should be appreciated that the depictedexample is merely intended to be illustrative and not limiting. Forexample, in other embodiments, the HVAC subsystem 12 may includemultiple scrubber units 70 and/or multiple air handling units 30.

In any case, as described above, an air handling unit 30 may providesupply air to a building zone 74. Thus, as in the depicted example, anair handling unit 30 may be fluidly coupled to a supply air duct 26.Additionally, as described above, an air handling unit 30 may producesupply air using any combination of return air and outside air. Thus, asin the depicted example, an air handling unit 30 may also be fluidlycoupled to a return air duct 28 and an outside air duct 76.

To facilitate producing supply air, the air handling unit 30 may includeone or more air dampers, one or more fans 80, one or more heat exchangercoils 82, and one or more fluid valves 84. For example, the air handlingunit 30 may include a first heat exchanger coil 74A, which is fluidlycoupled to a boiler 22 via a first supply fluid pipe 18A and a firstreturn fluid pipe 20A, and a second heat exchanger coil 74B, which isfluidly coupled to a chiller 24 via a second supply fluid pipe 18B and asecond return fluid pipe 20B. Additionally, the air handling unit 30 mayinclude a return air damper 78A, which is fluidly coupled between thereturn air duct 28 and an internal portion of the air handling unit 30,and an (e.g., first) outside air damper 78B, which is fluidly coupledbetween the outside air duct 76 and the internal portion of the airhandling unit 30. In some embodiments, a second outside air damper 78Bmay be fluidly coupled in the outside air duct 76 upstream of the firstoutside air damper 78B such that operation of the second outside airdamper 78B is controlled by the scrubber unit 70 while operation of thefirst outside air damper is controlled by the air handling unit 30.

In some embodiments, air handler control circuitry 86 may controloperation of equipment (e.g., devices or machines) in the air handlingunit 30, for example, based at least in part on target parameters (e.g.,temperature, humidity, and/or contaminant level) of supply air. Tofacilitate controlling operation, the air handler control circuitry 86may include a processor 88 and memory 90, for example, which selectivelyoperate in accordance with a supervisor clock signal or an internalclock signal. In some embodiments, the memory 90 may include one or moretangible, non-transitory, computer-readable media that storeinstructions executable by the processor 88 and/or data to be processedby the processor 88. For example, the memory 90 may include randomaccess memory (RAM), read only memory (ROM), flash memory, hard drives,optical discs, and/or the like. Additionally, the processor 88 mayinclude one or more general purpose microprocessors, one or moreapplication specific processors (ASICs), one or more field programmablelogic arrays (FPGAs), or any combination thereof.

Furthermore, as in the depicted example, the air handler controlcircuitry 86 may be communicatively coupled to one or more sensors 92and/or to one or more actuators 94, which is each mechanically coupledto a corresponding air damper 78 or fluid valve 84. In this manner, theair handler control circuitry 86 may receive sensor data indicative ofoperation parameters of the air handling unit 30. For example, based atleast in part on sensor data received from a sensor 92 coupled in thesupply air duct 26, the air handler control circuitry 86 may determinetemperature of supply air provided to the building zone 74 and controloperation of equipment in the air handling unit 30 based at least inpart on difference between the sensed temperature and a temperaturesetpoint (e.g., target temperature of the supply air) associated withthe building zone 74.

In some embodiments, air handler control circuitry 86 may controloperation of equipment by communicating one or more control commands(e.g., signals) to the equipment. For example, to control temperature ofsupply air, the air handler control circuitry 86 may transmit controlcommands that instruct an electric motor to adjust (e.g., modulate)speed of the fan 80, an actuator 94 to adjust valve position of a firstfluid valve 84A fluidly coupled to the first heat exchanger coil 82A,and/or an actuator 94 to adjust valve position of a second fluid valve84B fluidly coupled to the second heat exchanger coil 82B. To controlamount of return air and/or amount of outside air used to produce supplyair, the air handler control circuitry 86 may transmit control commandsthat instruct an actuator 94 to adjust damper position of the return airdamper 78A and/or an actuator 94 to adjust damper position of the (e.g.,first) outside air damper 78B.

In addition to the air dampers 78 implemented in the air handling unit30, in some embodiments, one or more air dampers may be implemented inother portions of an HVAC subsystem 12. For example, the HVAC subsystem12 may include an exhaust air damper 96 coupled in the return air duct28. Additionally, one or more air dampers may be implemented in thescrubber unit 70. As described above, a scrubber unit 70 may beimplemented to sorb (e.g., absorb or adsorb) contaminants from returnair, for example, while operating in a sorption mode. Thus, as in thedepicted example, a scrubber unit 70 may be fluidly coupled to thereturn air duct 28. In this manner, a scrubber unit 70 may facilitateincreasing amount of return air and, thus, reducing amount of outsideair used to produce supply air, which at least in some instances mayimprove operational efficiency of the HVAC subsystem 12.

To help illustrate, an example of a scrubber unit 70 is shown in FIG. 4.It should be appreciated that the depicted example is merely intended tobe illustrative and not limiting. In particular, specific arrangement ofthe components may vary between different scrubber unit 70 embodiments.

In any case, as in the depicted example, a housing 100 may enclose aninternal portion of a scrubber unit 70, which includes one or more fans102, one or more heaters 104, a flame shield 106, a contaminant filter108, a closed loop damper 110, and a particle filter 112. Additionally,the scrubber unit 70 may include a return inlet damper 114 and a returnoutlet damper 116 fluidly coupled between the internal portion and areturn air duct 28. Furthermore, the scrubber unit 70 may include anoutside inlet damper 118 and an outside outlet damper 120 fluidlycoupled between the internal portion and an outside air duct 76.

To facilitate adjusting damper position, an actuator 94 may bemechanically coupled to each air damper in the scrubber unit 70.Additionally, to facilitate monitoring operation, sensors 92 may beimplemented in the scrubber unit 70. For example, a return inlet sensor92A may be coupled on the return inlet damper 114 to facilitatedetermining parameters of return air flowing into the scrubber unit 70and a return outlet sensor 92B may be coupled on the return outletdamper 116 to facilitate determining characteristics of return airflowing out of the scrubber unit 70. Additionally, one or more filtersensors 92C may facilitate determining operational parameters, such astemperature of the contaminant filter 108 and/or pressure differentialacross the contaminant filter 108.

In some embodiments, the contaminant filter 108 may include one or morefilter cartridges, which each includes chemical compounds that sorb(e.g., absorb or adsorb) air contaminants when placed under certainenvironmental conditions. For example, when placed under an elevatedpressure differential condition, the chemical compounds may undergo afirst (e.g., forward) chemical reaction, which causes the each filtercartridge to sorb air contaminants from its surrounding environment.Additionally, when placed under an elevated temperature condition, thechemical compounds may undergo a second (e.g., reverse) chemicalreaction, which causes each filter cartridge to release previouslysorbed air contaminants into its surrounding environment.

Furthermore, in some embodiments, scrubber (e.g., dedicated) controlcircuitry may control operation of equipment (e.g., devices or machines)in the scrubber unit 70. For example, based at least in part on sensordata indicative of filter temperature, the scrubber control circuitrymay pulse the heater 104 on and off to control temperature of thecontaminant filter 108. Additionally, based at least in part on sensordata indicative of pressure differential, the scrubber control circuitrymay pulse the fan 102 on and off to control pressure differential acrossthe contaminant filter 108. In some embodiments, the scrubber controlcircuitry may be implemented in a control panel 122 formed on thehousing 100 of the scrubber unit 70.

To help illustrate, an example of a control panel 122 that includesscrubber control circuitry 124 is shown in FIG. 5. To facilitateimproving operational flexibility and/or serviceability, in someembodiments, the control panel 122 may be implemented using multiplemodules, for example, each physically enclosed by a separate housing. Inthe depicted example, the control panel 122 includes a controller module128, an input/output (I/O) module 130, a heater relay module 132, and afan relay module 134.

When implemented modularly, serviceability of the control panel 122 maybe improved, for example, by enabling a faulty module to be replacedwith little or no effect on other modules in the control panel 122. Asan illustrative example, the heater relay module 132 may be removed fromthe control panel 122 when identified as faulty and a replacement heaterrelay module 132 may be connected while the controller module 128, theI/O module 130, and the fan relay module 134 remain connected in thecontrol panel 122. In other words, modularly implementing the controlpanel 122 may facilitate targeting serving to relevant portions, forexample, instead of the control panel 122 as a whole.

Moreover, a modular implementation may facilitate improving operationalflexibility, for example, by enabling functionality provided by thecontrol panel 122 to be adaptively (e.g., dynamically) adjusted. As anillustrative example, the scrubber control circuitry 124 may communicatedata (e.g., sensor data, state data, and/or control commands) viainput/output (I/O) ports 126. However, in some embodiments, number ofI/O ports 126 implemented on the controller module 128 may be limited,for example, due to a balance between physical size and controlapplication compatibility.

Thus, as in the depicted example, the control panel 122 may beimplemented with a separate input/output (I/O) module 130, whichincludes additional I/O ports 126. By communicatively coupling the I/Omodule 130 to the controller module 128 via a communication bus 139(e.g., a sensor actuator bus and/or a field controller bus), number ofI/O ports 126 accessible by the scrubber control circuitry 124 may beincreased, which at least in some instances may facilitate improvingcontrol granularity and/or control transparency. For example, via an I/Oport 126 in the I/O module 130, the scrubber control circuitry 124 mayinstruct a switching device (e.g., relay or contractor) in the fan relaymodule 134 to electrically connect or disconnect the fan 102 and a powersource 136. Nevertheless, it should be appreciated that the depictedexample is merely intended to be illustrative and not limiting. Forexample, in other embodiments, the controller module 128 may beimplemented with sufficient number of I/O ports 126 such that a separateI/O module 130 is obviated.

In any case, to facilitate controlling operation, the scrubber controlcircuitry 124 may include a processor 138 and memory 140, for example,which selectively operate in accordance with a supervisor clock signalor an internal clock signal. In some embodiments, the memory 140 mayinclude one or more tangible, non-transitory, computer-readable mediathat store instructions executable by the processor 138 and/or data tobe processed by the processor 138. For example, the memory 140 mayinclude random access memory (RAM), read only memory (ROM), flashmemory, hard drives, optical discs, and/or the like. Additionally, theprocessor 138 may include one or more general purpose microprocessors,one or more application specific processors (ASICs), one or more fieldprogrammable logic arrays (FPGAs), or any combination thereof.

To operate the scrubber control circuitry 124, electrical power may besupplied from the power source 136 to the control panel 122. Since thepower source 136 may also supply electrical power to other electricalcomponents, in some embodiments, the power source 136 may be analternating current (AC) power source. To facilitate improvingoperational flexibility, in some embodiments, the controller module 128may operate using AC electrical power, for example, by internallyconverting the AC electrical power to direct current (DC) electricalpower. In other words, as an illustrative example, the control module128 may operate using twenty-four volt AC electrical power output from atransformer that receive one-hundred twenty volt AC electrical powerfrom the power source 136 (e.g., power grid).

In any case, as described above, the scrubber control circuitry 124 maycommunicate with equipment (e.g., sensor and/or actuators) in thescrubber unit 70 via the I/O ports 126. For example, the scrubbercontrol circuitry 124 may receive sensor data indicative of return airparameters (e.g., temperature, humidity, and/or contaminant level) fromthe return inlet sensor 92A and/or the return outlet sensor 92B viawires 141 coupled to the I/O ports 126. Additionally, the scrubbercontrol circuitry 124 may receive sensor data from one or more filtersensors 92C indicative of temperature and/or pressure differentialacross the contaminant filter 108 via wires 141 coupled to the I/O ports126. Furthermore, the scrubber control circuitry 124 may receiveparameter (e.g., state) data from a fan motor 143 indicative ofoperational parameters, such as speed of a corresponding fan 102, viawires 141 coupled to the I/O ports 126.

In addition to communicating parameter data with the fan motor 143, thescrubber control circuitry 124 may communicate control commands, forexample, that instruct the fan motor 143 to adjust (e.g., modulate)speed of the fan 102. Additionally or alternatively, the scrubbercontrol circuitry 124 may control fan speed by pulsing the fan 102 onand off, for example, by communicating control commands that instruct aswitching device in the fan relay module 134 to selectively connect anddisconnect electrical power. In a similar manner, the scrubber controlcircuitry 124 may control operation of the heater 104 by communicatingcontrol commands that instruct a switching device in the heater relaymodule 132 to selectively connect and disconnect electrical power, forexample, to pulse the heater 104 on and off. Furthermore, the scrubbercontrol circuitry 124 may communicate control commands to a return inletactuator 94A mechanically coupled to the return inlet damper 114, areturn outlet actuator 94B mechanically coupled to the return outletdamper 116, an outside inlet actuator 94C mechanically coupled to theoutside inlet damper 118, an outside outlet actuator 94D mechanicallycoupled to the outside outlet damper 120, and/or a closed loop actuator94E mechanically coupled to the closed loop damper 110, for example,that instructs an actuator 94 to adjust position of a correspondingdamper.

In some embodiments, the scrubber control circuitry 124 may additionallycommunicate with equipment, sensors, and/or other electronic devicesexternal from the scrubber unit 70. For example, the scrubber controlcircuitry 124 may communicate control commands to an external actuator94F mechanically coupled to the outside air damper 78B in the airhandling unit 30. The control commands may instruct the externalactuator 94F to adjust damper position of the outside air damper 78B,thereby enabling the scrubber control circuitry 124 to control amount ofoutside air available to the air handling unit 30 for producing supplyair.

In some embodiments, damper position of the outside air damper 78B maybe controlled based at least in part on operational state of the airhandling unit 30 and/or parameters (e.g., temperature, humidity, and/orcontaminant level) of outside air. To facilitate determining outside airparameters, in some embodiments, the scrubber control circuitry 124 maybe communicatively coupled to an outside air sensor 142, which outputssensor data indicative of the outside air parameters to the scrubbercontrol circuitry 124. Additionally or alternatively, the scrubbercontrol circuitry 124 may determine parameters of outside air based atleast in part on weather information, for example, received from thebuilding management system 34 or a remote data source 66. In any case,the scrubber control circuitry 124 may operate in this manner to controloperation of the scrubber unit 70 as well as other portions of the HVACsubsystem 12, such as the air handling unit 30.

To help illustrate, an example of a process 144 for operating scrubbercontrol circuitry 124 is described in FIG. 6. Generally, the process 144includes determining a controlling clock signal (process block 145),determining operational parameters of one or more building subsystems(process block 146), and controlling operation of a scrubber unit and/oran air handling unit (process block 148). In some embodiments, theprocess 144 may be implemented at least in part by executinginstructions stored in tangible, non-transitory, computer-readablemedia, such as memory 140, using processing circuitry, such as processor138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine a controlling clock signal (process block 145). As describedabove, in some embodiments, scrubber control circuitry 124 may generatean internal (e.g., local) clock signal to facilitate improvingimplementation flexibility, for example, by enabling a correspondingHVAC subsystem 12 and/or scrubber unit 70 to be deployed as a standalonesystem. Additionally, as described above, a building management system34 may supply a supervisor (e.g., global) clock signal to the HVACsubsystem 12, for example, to facilitate coordinating operation of HVACsubsystem 12 with the building management system 34 and/or anotherbuilding subsystem.

Thus, in some embodiments, the scrubber control circuitry 124 maydetermine the controlling clock signal by selecting between an internalclock signal and a supervisor control signal. To facilitate itsselection, in some embodiments, the scrubber control circuitry 124 maydetermine whether a corresponding scrubber unit 70 and/or HVAC subsystem12 is deployed as a standalone system or an integrated system, whichincludes a building management system 34. For example, when a supervisorcontrol signal is received, the scrubber control circuitry 124 maydetermine that the corresponding scrubber unit 70 and/or HVAC subsystem12 is deployed as an integrated system and, thus, select the supervisorcontrol signal as the controlling clock signal. On the other hand, whena supervisor control signal is not received, the scrubber controlcircuitry 124 may determine that the corresponding scrubber unit 70and/or HVAC subsystem 12 is deployed as a standalone system and, thus,select the internal control signal as the controlling clock signal. Insome embodiments, the scrubber control circuitry 124 may neverthelessselect the local clock signal as the controlling clock signal even whena supervisor control signal is received, for example, when scrubbercontrol circuitry 124 otherwise determines that the correspondingscrubber unit 70 and/or HVAC subsystem 12 is not deployed as anintegrated system.

Based at least in part on the controlling clock signal, the scrubbercontrol circuitry 124 may determine operational parameters associatedwith an HVAC subsystem 12 and/or other building subsystems (processblock 146). In some embodiments, operational parameters associated withan HVAC subsystem 12 may include operational parameters of a scrubberunit 70 in the HVAC subsystem 12, operational parameters of an airhandling unit 30 in the HVAC subsystem 12, and/or parameters of air(e.g., supply air, return air, and/or outside air) flowing through theHVAC subsystem 12. For example, the scrubber control circuitry 124 maydetermine return air parameters based at least in part on sensor datareceived from the return inlet sensor 92A and/or the return outletsensor 92B.

Based at least in part on sensor data received from the return inletsensor 92A and/or the return outlet sensor 92B, the scrubber controlcircuitry 124 may additionally or alternatively determine operationalparameters of the scrubber unit 70. For example, the scrubber controlcircuitry 124 may determine filtering efficiency of the contaminantfilter 108 based at least in part on contaminant level indicated by thereturn inlet sensor 92A compared to contaminant level indicated by thereturn outlet sensor 92B. Additionally, the scrubber control circuitry124 may determine temperature and/or pressure drop across thecontaminant filter 108 based at least in part on sensor data indicatedby one or more filter sensor 92C. In some embodiments, the scrubbercontrol circuitry 124 may additionally or alternatively receive anindication of other operational parameters associated with the HVACsubsystem 12, such as air handling unit 30 operational status, from theair handler control circuitry 86.

As described above, in some embodiments, operation of the HVAC subsystem12 may be controlled based at least in part on operational parametersassociated with other building subsystems, for example, to facilitateimproving operational efficiency by reducing power consumption resultingfrom operation of the HVAC subsystem 12. In some embodiments, thescrubber control circuitry 124 may receive an indication of operationalparameters directly from another building subsystem. Additionally oralternatively, the scrubber control circuitry 124 may receive anindication of operational parameters from the building management system34. For example, the building management system 34 may determineoccupancy (e.g., state) data indicative of occupancy status of abuilding zone 74 based at least in part on processing of sensor (e.g.,image) data captured by the security subsystem 40 and communicate theoccupancy data to the scrubber control circuitry 124.

Based at least in part on the operational parameters and the controllingclock signal, the scrubber control circuitry 124 may control operationof at least a portion of the HVAC subsystem 12, which includes an airhandling unit 30 and/or a scrubber unit 70 (process block 148). Asdescribed above, in some embodiments, the scrubber control circuitry 124may control operation of an air handling unit 30 by communicatingcontrol commands that instruct the external actuator 94F to adjustdamper position of an outside air damper 78B in the air handling unit30. In this manner, the scrubber control circuitry 124 may controlamount of outside air available to the air handling unit 30 forproducing supply air.

To control operation of a scrubber unit 70, the scrubber controlcircuitry 124 may communicate control commands that instruct the returninlet actuator 94A to adjust damper position of the return inlet damper114 and/or that instruct the outside inlet actuator 94C to adjust damperposition of the outside inlet damper 118. In this manner, the scrubbercontrol circuitry 124 may control source and/or flow of air into theinternal portion of the scrubber unit 70. Additionally, the scrubbercontrol circuitry 124 may communicate control commands that instruct thereturn outlet actuator 94B to adjust damper position of the returnoutlet damper 116 and/or that instruct the outside outlet actuator 94Dto adjust damper position of the outside outlet damper 120. In thismanner, the scrubber control circuitry 124 may control sink and/or flowof air out from the internal portion of the scrubber unit 70.

To control flow of air within the internal portion of the scrubber unit70, the scrubber control circuitry 124 may communicate control commandsthat instruct the closed loop actuator 94E to adjust damper position ofthe closed loop damper 110 and/or that instruct the fan motor 143 toadjust (e.g., modulate) speed of the fan 102. Additionally oralternatively, by communicating control commands that instruct the fanmotor 143 to adjust fan speed, the scrubber control circuitry 124 maycontrol pressure drop across the contaminant filter 108. To controltemperature of the contaminant filter 108, the scrubber controlcircuitry 124 may communicate control commands that instruct a switchingdevice in the heater relay module 132 to turn on the heater 104 byconnecting electrical power or to turn off the heater 104 bydisconnecting electrical power. For example, in this manner, the heater104 may be pulsed on and off to control temperature of the contaminantfilter 108 based at least in part on a target regeneration temperature.

To help further illustrate, an example of a process 150 for controllingoperation of a scrubber unit 70 is described in FIG. 7. Generally, theprocess 150 includes determining operational status of an air handlingunit (process block 152), determining whether the operational status ofthe air handling unit is on (decision block 154), determiningcontaminant level in return air when the air handling unit is on(process block 156), determining whether the contaminant level isgreater than a lower threshold (decision block 158), and operating thescrubber unit in a standby mode when the air handling unit is not onand/or when the contaminant level is not greater than the lowerthreshold (process block 160). When the contaminant level is greaterthan the lower threshold, the process 150 includes determining whetherthe contaminant level is greater than an upper threshold (decision block162) and operating the scrubber unit in a sorption mode when thecontaminant level is greater than the upper threshold (process block164). When the contaminant level is not greater than the upperthreshold, the process 150 includes determining filtering efficiency ofthe scrubber unit (process block 166), determining whether the filteringefficiency is less than an efficiency threshold (decision block 168),and operating the scrubber unit in a regeneration mode when thefiltering efficiency is less than the efficiency threshold (processblock 170). In some embodiments, the process 150 may be implemented atleast in part by executing instructions stored in tangible,non-transitory, computer-readable media, such as memory 140, usingprocessing circuitry, such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine operational status of an air handling unit 30, for example,implemented in the same HVAC subsystem 12 as a corresponding scrubberunit 70 (process block 152). As described above, in some embodiments,the scrubber control circuitry 124 may receive an indication ofoperational status and/or other operational parameters associated withan air handling unit 30 from corresponding air handler control circuitry86. Additionally or alternatively, the scrubber control circuitry 124may receive an indication of the operational parameters associated withthe air handling unit 30 from the building management system 34. Forexample, the scrubber control circuitry 124 may determine operationalstatus of an air handling unit 30 based at least in part on receivedparameter (e.g., state) data, which indicates whether the air handlingunit 30 in an on state or an off state.

When the air handling unit 30 is on, the scrubber control circuitry 124may determine contaminant level present in return air (process block156) and determine whether the contaminant level is greater than acontaminant level lower threshold (decision block 158). As describedabove, in some embodiments, the scrubber control circuitry 124 maydetermine contaminant level present in return air based at least in parton sensor data received from the return inlet sensor 92A and/or sensordata received from the return outlet sensors 92B. Additionally, in someembodiments, the contaminant level lower threshold may predetermined andstored in a tangible, non-transitory, computer-readable medium, such asmemory 140. Thus, in such embodiments, the scrubber control circuitry124 may retrieve the contaminant level lower threshold from thetangible, non-transitory, computer-readable medium and compare thecontaminant level present in return air with the contaminant level lowerthreshold. Furthermore, in some embodiments, the contaminant level lowerthreshold may be set less based at least in part on target contaminantlevel of supply air, for example, such that the contaminant lowerthreshold is less than or equal to the target contaminant level.

Accordingly, when the contaminant level is not greater than thecontaminant level lower threshold and/or the air handling unit 30 is noton, the scrubber control circuitry 124 may determine that use of returnair to produce supply air is not limited by return air contaminant leveland, thus, instruct the scrubber unit 70 to operate in a standby mode(process block 160). While operating in the standby mode, at least aportion of return air may flow through the scrubber unit 70 without thescrubber unit 70 actively introducing a pressure differential across itscontaminant filter 108. In this manner, the scrubber control circuitry124 may continue monitoring parameters of return air using the returninlet sensor 92A and/or the return outlet sensor 92B while the scrubberunit 70 is not actively sorbing or releasing previously sorbed aircontaminants. At least in some instances, this may facilitate reducingimplementation associated cost of an HVAC subsystem 12, for example, byobviating implementation of additional sensors 92 for determination ofreturn air parameters.

To help illustrate, an example of a process 172 for operating a scrubberunit 70 in a standby mode is described in FIG. 8. Generally, the process172 includes maintaining a return inlet damper and a return outletdamper in an open position (process block 174), maintaining an outsideinlet damper and an outside outlet damper in a closed position (processblock 176), maintaining a closed loop damper in a closed position(process block 180), maintaining a fan off (process block 180), andmaintaining a heater off (process block 182). In some embodiments, theprocess 172 may be implemented at least in part by executinginstructions stored in tangible, non-transitory, computer-readablemedia, such as memory 140, using processing circuitry, such as processor138.

Accordingly, in some embodiments, scrubber control circuitry 124 maycontrol operation of a scrubber unit 70 such that its return inletdamper 114 and return outlet damper 116 are both maintained in an atleast partially open position (process block 174). While operating inthe standby mode, in some embodiments, damper position of the returninlet damper 114 and/or the return outlet damper 116 may be controlledbased at least in part on a target standby damper position. For example,the scrubber control circuitry 124 may instruct the return inletactuator 94A to transition to and/or maintain damper position of thereturn inlet damper 114 in an at least partially open position, therebyenabling return air to flow from the return air duct 28 into theinternal portion of the scrubber unit 70. Similarly, the scrubbercontrol circuitry 124 may instruct the return outlet actuator 94B totransition to and/or maintain damper position of the return outletdamper 116 in an at least partially open position, thereby enablingreturn air to flow from the internal portion of the scrubber unit 70back into the return air duct 28.

Additionally, the scrubber control circuitry 124 may control operationof the scrubber unit 70 such that its outside inlet damper 118 and itsoutside outlet damper 120 are both maintained in a fully closed position(process block 176). For example, the scrubber control circuitry 124 mayinstruct the outside inlet actuator 94C to transition to and/or maintainthe outside inlet damper 118 in a fully closed position, therebyblocking outside air from flowing into the internal portion of thescrubber unit 70. Similarly, the scrubber control circuitry 124 mayinstruct the outside outlet actuator 94D to transition to and/ormaintain the outside outlet damper 120 in a fully closed position,thereby blocking flow of return air from the internal portion of thescrubber unit 70 to an outside air duct 76.

Furthermore, the scrubber control circuitry 124 may control operation ofthe scrubber unit 70 such that its closed loop damper 110 is maintainedin a fully closed position (process block 178). For example, thescrubber control circuitry 124 may instruct the closed loop actuator 94Eto transition to and/or maintain the closed loop damper 110 in a fullyclosed position. In this manner, the scrubber control circuitry 124 mayreduce likelihood of return air being trapped within the internalportion of scrubber unit 70. At least in some instances this mayfacilitate improving accuracy of return air parameter determination bythe return inlet sensor 92A and/or the return outlet sensor 92B, forexample, when return air parameters vary significantly (e.g.,noticeably) over time.

The scrubber control circuitry 124 may also control operation of thescrubber unit 70 such that its fan 102 is maintained in an off state(process block 180) and such that its heater 104 is maintained in an offstate (process block 182). To maintain the fan 102 off, in someembodiments, the scrubber control circuitry 124 may instruct the fanmotor 143 to maintain speed of the fan 102 at zero. Additionally oralternatively, the scrubber control circuitry 124 may instruct aswitching device in the fan relay module 134 to switch to and/ormaintain an open position, thereby disconnecting electrical power fromthe fan 102. Similarly, in some embodiments, the scrubber controlcircuitry 124 may maintain the heater 104 off by instructing a switchingdevice in the heater relay module 132 to switch to and/or maintain anopen position, thereby disconnecting electrical power from the heater104. In this manner, a scrubber unit 70 may operate in the standby modeto facilitate continued monitoring of return air parameters using itsreturn inlet sensor 92A and/or return outlet sensor 92B, which at leastin some instances may facilitate reducing implementation associated costof an HVAC subsystem 12, for example, by obviating implementation ofadditional sensors for determination of return air parameters.

Returning to the process 150 of FIG. 7, when contaminant level presentin return air is greater than the contaminant level lower threshold, thescrubber control circuitry 124 may determine whether the contaminantlevel is greater than a contaminant level upper threshold (decisionblock 162). As with the contaminant level lower threshold, in someembodiments, the contaminant level upper threshold may predetermined andstored in a tangible, non-transitory, computer-readable medium, such asmemory 140. Thus, in such embodiments, the scrubber control circuitry124 may retrieve the contaminant level upper threshold from thetangible, non-transitory, computer-readable medium and compare thecontaminant level present in return air with the contaminant level upperthreshold. Furthermore, in some embodiments, the contaminant level upperthreshold may be set based at least in part on target contaminant levelof supply air, for example, such that the contaminant level upperthreshold is at or above the target contaminant level.

Accordingly, when the contaminant level is greater than the contaminantlevel upper threshold, the scrubber control circuitry 124 may determinethat use of return air to produce supply air is limited by return aircontaminant level and, thus, instruct the scrubber unit 70 to operate ina sorption mode (process block 164). While operating in the sorptionmode, the scrubber unit 70 may actively introduce a pressuredifferential across its contaminant filter 108, which causes chemicalcompounds in the contaminant filter 108 to sorb (e.g., adsorb or absorb)air contaminants from return air flowing through the scrubber unit 70.In this manner, the scrubber unit 70 may facilitate reducing contaminantlevel present in return air, which at least in some instances mayfacilitate improving operational efficiency of an HVAC subsystem 12, forexample, by enabling supply air to be produced using more return airand/or less outside air.

To help illustrate, an example of a process 184 for operating a scrubberunit 70 in a sorption mode is described in FIG. 9. Generally, theprocess 184 includes maintaining a return inlet damper and a returnoutlet damper in an open position (process block 186), maintaining anoutside inlet damper and an outside outlet damper in a closed position(process block 188), maintaining a closed loop damper in a closedposition (process block 190), modulating fan speed based on a targetpressure differential (process block 192), and maintaining a heater off(process block 194). In some embodiments, the process 184 may beimplemented at least in part by executing instructions stored intangible, non-transitory, computer-readable media, such as memory 140,using processing circuitry, such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maycontrol operation of a scrubber unit 70 such that its return inletdamper 114 and its return outlet damper 116 are both maintained in an atleast partially open position (process block 186). While operating inthe sorption mode, in some embodiments, damper position of the returninlet damper 114 and/or the return outlet damper 116 may be controlledbased at least in part on a target sorption damper position. Forexample, the scrubber control circuitry 124 may instruct the returninlet actuator 94A to transition to and/or maintain damper position ofthe return inlet damper 114 in an at least partially open position,thereby enabling return air to flow from the return air duct 28 into theinternal portion of the scrubber unit 70. Similarly, the scrubbercontrol circuitry 124 may instruct the return outlet actuator 94B totransition to and/or maintain damper position of the return outletdamper 116 in an at least partially open position, thereby enablingreturn air to flow from the internal portion of the scrubber unit 70back into the return air duct 28.

Additionally, the scrubber control circuitry 124 may control operationof the scrubber unit 70 such that its outside inlet damper 118 and itsoutside outlet damper 120 are both maintained in a fully closed position(process block 188). For example, the scrubber control circuitry 124 mayinstruct the outside inlet actuator 94C to transition to and/or maintainthe outside inlet damper 118 in a fully closed position, therebyblocking outside air from flowing into the internal portion of thescrubber unit 70. Similarly, the scrubber control circuitry 124 mayinstruct the outside outlet actuator 94D to transition to and/ormaintain the outside outlet damper 120 in a fully closed position,thereby blocking flow of return air from the internal portion of thescrubber unit 70 to an outside air duct 76.

Furthermore, the scrubber control circuitry 124 may control operation ofthe scrubber unit 70 such that the closed loop damper 110 is maintainedin a fully closed position (process block 190). For example, when theclosed loop damper 110 is in an at least partially open position, thescrubber control circuitry 124 may instruct the closed loop actuator 94Eto transition to and/or maintain the closed loop damper 110 in a fullyclosed position. In this manner, the scrubber control circuitry 124 mayreduce likelihood of filtered return air being re-circulated through theinternal portion of scrubber unit 70, which at least in some instancesmay facilitate improving operational stability, for example, due tocontaminant level in return air gradually changing over time.

As described above, in some embodiments, the contaminant filter 108 in ascrubber unit 70 may be implemented (e.g., designed) to sorb aircontaminants under specific temperature and/or pressure differentialconditions. For example, the contaminant filter 108 may sorb aircontaminants when its temperature is below a temperature threshold andthe pressure differential across the contaminant filter 108 is above apressure threshold. Thus, while operating in the sorption mode, thescrubber control circuitry 124 may control operation of the scrubberunit 70 such that the heater 104 is maintained in an off state (processblock 194). To maintain the heater 104 off, in some embodiments, thescrubber control circuitry 124 may instruct a switching device in theheater relay module 132 to switching to and/or maintain an openposition, thereby disconnecting electrical power from the heater 104.

Additionally, the scrubber control circuitry 124 may also controloperation of the fan 102 to actively introduce a pressure differentialacross the contaminant filter 108 based at least in part on a targetsorption pressure differential (process block 192). For example, whenpressure differential across the contaminant filter 108 resulting frommaintaining the fan 102 off is less than the target sorption pressuredifferential, the scrubber control circuitry 124 may instruct the fanmotor 143 to actuate (e.g., rotate) the fan 102, thereby forcing airthrough and, thus, increasing the pressure differential across thecontaminant filter 108. Generally, the pressure differential across thecontaminant filter 108 may vary based at least in part on speed at whichthe fan 102 rotates. To facilitate sorbing air contaminants, in someembodiments, the target sorption pressure differential may set based atleast in part on the pressure threshold, for example, such that thetarget sorption pressure differential includes a range of pressuredifferentials at or above the pressure threshold. In this manner, ascrubber unit 70 may operate in the sorption mode to facilitate reducingcontaminant level present in return air, which at least in someinstances may facilitate improving operational efficiency of an HVACsubsystem 12, for example, by increasing amount of return air and/orreducing amount of outside air used to produce supply air.

Returning to the process 150 of FIG. 7, when the contaminant levelpresent in return air is not greater than the contaminant level upperthreshold, the scrubber control circuitry 124 may determine filteringefficiency of the contaminant filter 108 in the scrubber unit 70(process block 166). As described above, in some embodiments, filteringefficiency of a contaminant filter 108 may be determined based at leastin part on contaminant level present before passing through thecontaminant filter 108 and contaminant level present after passingthrough the contaminant filter 108. Thus, in such embodiments, thescrubber control circuitry 124 may determine filtering efficiency basedat least in part on sensor data received from the return inlet sensor92A and sensor data received from the return outlet sensor 92B. Forexample, the scrubber control circuitry 124 may determine the filteringefficiency as a ratio of contaminant level present in return air flowinginto the scrubber unit 70 and amount of contaminants sorbed from thereturn air (e.g., input contaminant level minus output contaminantlevel).

As a contaminant filter 108 continues to sorb air contaminants, in someembodiments, filtering efficiency of the contaminant filter 108 maygradually decrease, thereby reducing amount of air contaminants sorbedduring subsequent operation. To facilitate improving filteringefficiency provided during subsequent operation, the scrubber controlcircuitry 124 may determine whether the current filtering efficiency isless than a filtering efficiency threshold (decision block 168) andinstruct the scrubber unit 70 to operate in a regeneration mode when thecurrent filtering efficiency is less than the filtering efficiencythreshold (process block 170). In some embodiments, the filteringefficiency threshold may predetermined and stored in a tangible,non-transitory, computer-readable medium, such as memory 140. Thus, insuch embodiments, the scrubber control circuitry 124 may retrieve thefiltering efficiency threshold from the tangible, non-transitory,computer-readable medium and compare the current filtering efficiencywith the filtering efficiency threshold. Additionally, by operating in aregeneration mode, previously sorbed air contaminants may be vented(e.g., exhausted and/or released) from the scrubber unit 70, which atleast in some instances may facilitate improving filtering efficiencyand, thus, amount of air contaminants sorbed during subsequentoperation.

To help illustrate, an example of a process 196 for operating a scrubberunit 70 in a regeneration mode is described in FIG. 10. Generally, theprocess 196 includes operating in a closed loop heating phase (processblock 198), operating in a bleed phase (process block 200), andoperating in a cool down phase (process block 202). In some embodiments,the process 196 may be implemented at least in part by executinginstructions stored in tangible, non-transitory, computer-readablemedia, such as memory 140, using processing circuitry, such as processor138.

Accordingly, in some embodiments, scrubber control circuitry 124 mayinstruct a scrubber unit 70 to operate in the closed loop heating phase(process block 198). As described above, in some embodiments, acontaminant filter 108 may release previously sorbed air contaminantswhen its temperature is above a temperature threshold. Thus, whentemperature of return air is less than the temperature threshold, thescrubber control circuitry 124 may control operation of the scrubberunit 70 to increase temperature of the contaminant filter 108 above thetemperature threshold during the closed loop heating phase.

To help illustrate, an example of a process 204 for operating a scrubberunit 70 in a closed loop heating phase of a regeneration mode isdescribed in FIG. 11. Generally, the process 204 includes maintaining areturn inlet damper and a return outlet damper in a closed position(process block 206), maintaining an outside inlet damper and an outsideoutlet damper in a closed position (process block 208), maintaining aclosed loop damper in an open position (process block 210), maintaininga fan on (process block 212), and pulsing a heater on based on a targettemperature (process block 214). In some embodiments, the process 204may be implemented at least in part by executing instructions stored intangible, non-transitory, computer-readable media, such as memory 140,using processing circuitry, such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maycontrol operation of a scrubber unit 70 such that its return inletdamper 114 and return outlet damper 116 are both maintained in a fullyclosed position (process block 206). For example, the scrubber controlcircuitry 124 may instruct the return inlet actuator 94A to transitionto and/or maintain the return inlet damper 114 in a fully closedposition, thereby blocking flow of return air into the internal portionof the scrubber unit 70. Similarly, the scrubber control circuitry 124may instruct the return outlet actuator 94B to transition to and/ormaintain the return outlet damper 116 in a fully closed position,thereby blocking flow of air out from the internal portion of thescrubber unit 70 to a return air duct 28.

Additionally, the scrubber control circuitry 124 may control operationof the scrubber unit 70 such that its outside inlet damper 118 and itsoutside outlet damper 120 are both maintained in a fully closed position(process block 208). For example, the scrubber control circuitry 124 mayinstruct the outside inlet actuator 94C to transition to and/or maintainthe outside inlet damper 118 in a fully closed position, therebyblocking outside air from flowing into the internal portion of thescrubber unit 70. Similarly, the scrubber control circuitry 124 mayinstruct the outside outlet actuator 94D to transition to and/ormaintain the outside outlet damper 120 to a fully closed position,thereby blocking flow of air from the internal portion of the scrubberunit 70 to an outside air duct 76.

Furthermore, the scrubber control circuitry 124 may control operation ofthe scrubber unit 70 such that its closed loop damper 110 is maintainedin an at least partially open position (process block 210). Whileoperating in the standby mode, in some embodiments, damper position ofthe closed loop damper 110 may be controlled based at least in part on atarget closed loop heating damper position. For example, the scrubbercontrol circuitry 124 may instruct the outside inlet actuator 94C totransition to and/or maintain the outside inlet damper 118 in a fully(e.g., 100%) open position, thereby enabling air circulation within theinternal portion of the scrubber unit 70.

To facilitate controlling air circulation within the scrubber unit 70,the scrubber control circuitry 124 may control operation the scrubberunit such that its fan 102 is maintained on (process block 212). Forexample, the scrubber control circuitry 124 may instruct the fan motor143 to maintain the fan 102 at a target (e.g., maximum or substantiallyconstant) speed. By maintaining the fan 102 on, circulated air may flowthrough the contaminant filter 108 and, thus, temperature of thecontaminant filter 108 may be dependent on temperature of the circulatedair.

Thus, to facilitate controlling temperature of the contaminant filter108, the scrubber control circuitry 124 may control operation the heater104 based at least in part on a target regeneration temperatureassociated with the contaminant filter 108 (process block 214). Forexample, when temperature of the contaminant filter 108 is below thetarget regeneration temperature, the scrubber control circuitry 124 mayturn on the heater 104 by instructing a switching device in the heaterrelay module 132 to connect electrical power to the heater 104. On theother hand, when temperature of the contaminant filter 108 is above thetarget regeneration temperature, the scrubber control circuitry 124 mayturn off the heater 104 by instructing the switching device in theheater relay module 132 to disconnect electrical power from the heater104.

As described above, in some embodiments, a contaminant filter 108 mayrelease previously sorbed air contaminants when its temperature is abovea temperature threshold. Thus, in such embodiments, the targetregeneration temperature may set based at least in part on thetemperature threshold, for example, such that the target regenerationtemperature includes a range of temperature at or above the temperaturethreshold. In this manner, a scrubber unit 70 may operate in a closedloop heating phase of a regeneration mode to facilitate releasingpreviously sorbed air contaminants, for example, by pulsing its heater104 pulsed on and off to increase temperature of the contaminant filter108 above its normal operating (e.g., standby or sorption) temperature.

Returning to the process 196 of FIG. 10, after the closed loop heatingphase, the scrubber control circuitry 124 may instruct the scrubber unit70 to operate in the bleed phase (process block 200). As describedabove, during the closed loop heating phase, temperature of thecontaminant filter 108 may be controlled such that the contaminantfilter 108 releases previously sorbed air contaminants. To reducelikelihood of released air contaminants merely being re-sorbed by thecontaminant filter 108, the scrubber control circuitry 124 may controloperation of the scrubber unit 70 to vent (e.g., exhaust) the releasedair contaminants during the bleed phase.

To help illustrate, an example of a process 216 for operating a scrubberunit 70 in a bleed phase of a regeneration mode is described in FIG. 12.Generally, the process 216 includes determining a parameter of outsideair (process block 218), determining whether the parameter of theoutside air is within a target range (decision block 220), and, when theparameter is within the target range, maintaining a return inlet damperand a return outlet damper in a closed position (process block 222), andramping an outside inlet damper and an outside outlet damper from aclosed position toward an open position (process block 224). When theparameters are not within the target range, the process 216 includesramping the return inlet damper and the outside outlet damper from aclosed position toward an open position (process block 226) andmaintaining the outside inlet damper and the return outlet damper in aclosed position (process block 228). Additionally, the process 216includes ramping a closed loop damper from an open position toward aclosed position (process block 230), maintaining a fan on (process block232), and pulsing a heater on based on a target temperature (processblock 234). In some embodiments, the process 216 may be implemented atleast in part by executing instructions stored in tangible,non-transitory, computer-readable media, such as memory 140, usingprocessing circuitry, such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine parameters of outside air, such as temperature, humidity,and/or contaminant level (process block 218). As described above, insome embodiments, the scrubber control circuitry 124 may determineparameters of outside air based at least in part on sensor data receivedfrom an outside air sensor 142. Additionally or alternatively, thescrubber control circuitry 124 may determine parameters of outside airbased at least in part on weather data, for example, received by thebuilding management system 34 from a remote data source 66 andcommunicated from the building management system 34 to the scrubbercontrol circuitry 124.

Based at least in part on whether the outside air parameters are withincorresponding target ranges, the scrubber control circuitry 124 maydetermine whether the outside air is suitable for venting (e.g.,exhausting) released air contaminants from the scrubber unit 70(decision block 220). In particular, as described above, a contaminantfilter 108 may release previously sorbed air contaminants when itstemperature is above a temperature threshold. As such, temperature ofair used to vent released air contaminants may affect temperature of thecontaminant filter 108 and, thus, release of previously sorbed aircontaminants. For example, using cold air to vent the scrubber unit 70may result in the contaminant filter 108 prematurely ceasing release ofsorbed air contaminants (e.g., before entering the cool down phase).

Thus, in some embodiments, the scrubber control circuitry 124 maydetermine suitability of outside air for venting based at least in parton whether temperature of the outside air is within a target ventingtemperature range, for example, above a low temperature threshold. Insome embodiments, release of previously sorbed air contaminants mayadditionally or alternatively be affected by other parameters of ventingair, such as humidity. Thus, in such embodiments, the scrubber controlcircuitry 124 may determine suitability of outside air for venting basedat least in part on whether humidity of the outside air is within atarget venting humidity range, for example, above a lower humiditythreshold and below an upper humidity threshold.

When the parameters are indicative of outside air being suitable forventing, the scrubber control circuitry 124 may control operation of thescrubber unit 70 such that it outside inlet damper 118 and its outsideoutlet damper 120 are both ramped from a fully closed position toward anopen position (process block 224) while its return inlet damper 114 andits return outlet damper 116 are both maintained in a fully closedposition (process block 222). For example, when in a fully closedposition (e.g., 0% open) during the closed loop heating phase, thescrubber control circuitry 124 may instruct the outside inlet actuator94C to transition to and/or maintain the outside inlet damper 118 at a10% open position and the outside outlet actuator 94D to transition toand/or maintain the outside outlet damper 120 at a 10% open positionduring a first duration in the bleed phase. During a second duration inthe bleed phase after the first duration, the scrubber control circuitry124 may instruct the outside inlet actuator 94C to transition to and/ormaintain the outside inlet damper 118 at a 20% open position and theoutside outlet actuator 94D to transition to and/or maintain the outsideoutlet damper 120 to a 20% open position. Additionally, the scrubbercontrol circuitry 124 may instruct the outside inlet actuator 94C totransition to and/or maintain the outside inlet damper 118 at a 30% openposition and the outside outlet actuator 94D to transition to and/ormaintain the outside outlet damper 120 to a 30% open position during athird duration in the bleed phase after the second duration. During afourth duration in the bleed phase after the third duration, thescrubber control circuitry 124 may instruct the outside inlet actuator94C to transition to and/or maintain the outside inlet damper 118 at a40% open position and the outside outlet actuator 94D to transition toand/or maintain the outside outlet damper 120 at a 40% open position.Furthermore, the scrubber control circuitry 124 may instruct the outsideinlet actuator 94C to transition to and/or maintain the outside inletdamper 118 at a 50% open position and the outside outlet actuator 94D totransition to and/or maintain the outside outlet damper 120 at a 50%open position during a fifth duration in the bleed phase after thefourth duration.

In some embodiments, amount of air contaminants released from acontaminant filter 108 generally increases the longer temperature of thecontaminant filter 108 is maintained at a target regenerationtemperature (e.g., temperature above the temperature threshold). Sincetemperature of outside air is generally lower than the targetregeneration temperature, gradually ramping damper position of theoutside inlet damper 118 and/or the outside outlet damper 120 mayfacilitate increasing duration temperature of the contaminant filter ismaintained at the target regeneration temperature and, thus, amount ofpreviously sorbed air contaminants that is released from the contaminantfilter 108 during a regeneration cycle. In fact, in some embodiments,the scrubber control circuitry 124 may select one of multipleregeneration modes, which each have varying total durations.

For example, the scrubber control circuitry 124 may select from a quickregeneration mode, a standard regeneration mode, and an extendedregeneration mode. In some embodiments, the quick regeneration mode, thestandard regeneration mode, and the extended regeneration mode may havediffering bleed phases. For example, in the quick regeneration mode, thefirst duration during its bleed phase may be eight minutes, the secondduration during its bleed phase may be five minutes, the third durationduring its bleed phase may be three minutes, the fourth duration duringits bleed phase may be two minutes, and the fifth duration during itsbleed phase may be two minutes. Additionally, in the standardregeneration mode, the first duration during its bleed phase may betwenty minutes, the second duration during its bleed phase may befifteen minutes, the third duration during its bleed phase may befifteen minutes, the fourth duration during its bleed phase may be tenminutes, and the fifth duration during its bleed phase may be tenminutes. Furthermore, in the extended regeneration mode, the firstduration during its bleed phase may be forty minutes, the secondduration during its bleed phase may be thirty-five minutes, the thirdduration during its bleed phase may be thirty minutes, the fourthduration during its bleed phase may be twenty-five minutes, and thefifth duration during its bleed phase may be twenty minutes.

In other words, in some embodiments, each of the multiple regenerationmodes may provide differing tradeoffs between duration a scrubber unit70 is unavailable to operate in the sorption mode and filteringefficiency available during subsequent operation. Since contaminantlevel present in return air is generally higher when a building 10 isoccupied, in some embodiments, the scrubber control circuitry 124 mayselect between the multiple regeneration modes based at least in part onoccupancy status (e.g., current occupancy and/or expected futureoccupancy) of the building 10 as will be described in more detail below.In any case, by operating in this manner, a scrubber unit 70 may vent(e.g., exhaust) released air contaminants using outside air during ableed phase of a regeneration mode when parameters of the outside airare acceptable (e.g., within corresponding target ranges).

On the other hand, when outside air is not suitable for venting, thescrubber control circuitry 124 may control operation of the scrubberunit 70 such that the return inlet damper 114 and the outside outletdamper 120 are both ramped from a fully closed position toward an openposition (process block 226) while the outside inlet damper 118 and thereturn outlet damper 116 are both maintained in a fully closed position(process block 228). In other words, when parameters of outside air areindicative of the outside air being unsuitable for venting, the scrubbercontrol circuitry 124 may instruct the scrubber unit 70 to instead ventreleased air contaminants using return air, which at least in someinstances may facilitate improving subsequent filtering efficiency, forexample, compared to venting using outside air with parameters outsidecorresponding target parameter ranges. Nevertheless, in a similar manneras the outside outlet damper 120, the scrubber control circuitry 124 maygradually ramp the return inlet damper 114 from a fully closed positiontoward an open position to facilitate increasing amount of aircontaminants released from the contaminant filter 108 and, thus,filtering efficiency provided during subsequent operation.

For example, when in a fully closed (e.g., 0% open) position during theclosed loop heating phase, the scrubber control circuitry 124 mayinstruct the return inlet actuator 94A to transition to and/or maintainthe return inlet damper 114 at a 10% open position and the outsideoutlet actuator 94D to transition to and/or maintain the outside outletdamper 120 at a 10% open position during the first duration in the bleedphase. During the second duration in the bleed phase, the scrubbercontrol circuitry 124 may instruct the return inlet actuator 94A totransition to and/or maintain the return inlet damper 114 at a 20% openposition and the outside outlet actuator 94D to transition to and/ormaintain the outside outlet damper 120 at a 20% open position.Additionally, the scrubber control circuitry 124 may instruct the returninlet actuator 94A to transition to and/or maintain the return inletdamper 114 at a 30% open position and the outside outlet actuator 94D totransition to and/or maintain the outside outlet damper 120 at a 30%open position during the third duration in the bleed phase. During thefourth duration in the bleed phase, the scrubber control circuitry 124may instruct the outside inlet actuator to transition to and/or maintainthe return inlet damper 114 at a 40% open position and the outsideoutlet actuator 94D to transition to and/or maintain the outside outletdamper 120 at a 40% open position. Furthermore, the scrubber controlcircuitry 124 may instruct the return inlet actuator 94A to transitionto and/or maintain the return inlet damper 114 at a 50% open positionand the outside outlet actuator 94D to transition to and/or maintain theoutside outlet damper 120 at a 50% open position during the fifthduration in the bleed phase.

In any case, the scrubber control circuitry 124 may also controloperation of the scrubber unit 70 such that its closed loop damper 110is maintained in an at least partially open position (process block230), the fan 102 is maintained on (process block 232), and the heater104 is pulsed on based at least in part on target regenerationtemperature associated with the contaminant filter 108 (process block234), thereby enabling heated air to continue being circulated withinthe scrubber unit 70. In some embodiments, the scrubber controlcircuitry 124 may gradually ramp the closed loop damper 110 toward aclosed position during the bleed phase. For example, when in a fully(e.g., 100%) open position during the closed loop heating phase, thescrubber control circuitry 124 may instruct the closed loop actuator 94Eto transition to and/or maintain the closed loop damper at a 90% openposition during the first duration in the bleed phase. During the secondduration in the bleed phase, the scrubber control circuitry 124 mayinstruct the closed loop actuator 94E to transition to and/or maintainthe closed loop damper 110 at an 80% open position. Additionally, thescrubber control circuitry 124 may instruct the closed loop actuator 94Eto transition to and/or maintain the closed loop damper 110 at a 70%open position during the third duration in the bleed phase. During thefourth duration in the bleed phase, the scrubber control circuitry 124may instruct the closed loop actuator 94E to transition to and/ormaintain the closed loop damper 110 at a 60% open position. Furthermore,the scrubber control circuitry 124 may instruct the closed loop actuator94E to transition to and/or maintain the closed loop damper 110 at a 50%open position during the fifth duration in the bleed phase.

In other words, in some embodiments, the scrubber control circuitry 124may ramp damper position of the closed loop damper 110 in coordinationwith the outside outlet damper 120 during the bleed phase. In any case,by operating in this manner, a scrubber unit 70 may vent (e.g., exhaust)released air contaminants during a bleed phase of a regeneration mode.Moreover, the scrubber unit 70 may continue maintaining temperature ofits contaminant filter 108 at the target regeneration temperature toenable the contaminant filter 108 to continue releasing previouslysorbed air contaminants during the bleed phase, which at least in someinstances may facilitate improving filtering efficiency available duringsubsequent operation.

Returning to the process 196 of FIG. 10, after the bleed phase, thescrubber control circuitry 124 may instruct the scrubber unit 70 tooperate in the cool down phase (process block 202). As described above,temperature of a contaminant filter 108 may be elevated above its normal(e.g., standby or sorption) operating temperature during the closed loopheating phase and/or the bleed phase. Additionally, as described above,a contaminant filter 108 may sorb air contaminants when its temperatureis below a temperature threshold. Thus, to facilitate subsequentlyoperating in the sorption mode, the scrubber control circuitry 124 maycontrol operation of the scrubber unit 70 to reduce temperature of thecontaminant filter 108 during the cool down phase.

To help illustrate, an example of a process 236 for operating a scrubberunit 70 in a cool down phase of a regeneration mode is described in FIG.13. Generally, the process 236 includes determining parameters ofoutside air (process block 238), determining whether the parameters ofthe outside air are acceptable (decision block 240), and, when theparameters are acceptable, maintaining a return inlet damper and areturn outlet damper in a closed position (process block 242), andmaintaining an outside inlet damper and an outside outlet damper in apartially open position (process block 244). When the parameters are notacceptable, the process 236 includes maintaining the return inlet damperand the outside outlet damper in a partially open position (processblock 246) and maintaining the outside inlet damper and the returnoutlet damper in a closed position (process block 248). Additionally,the process 236 includes maintaining a closed loop damper in a partiallyopen position (process block 250), maintaining a fan on (process block252), and maintaining a heater off (process block 254). In someembodiments, the process 236 may be implemented at least in part byexecuting instructions stored in tangible, non-transitory,computer-readable media, such as memory 140, using processing circuitry,such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine parameters of outside air, such as temperature, humidity,and/or contaminant level (process block 238). As described above, insome embodiments, the scrubber control circuitry 124 may determineparameters of outside air based at least in part on sensor data receivedfrom an outside air sensor 142. Additionally or alternatively, thescrubber control circuitry 124 may determine parameters of outside airbased at least in part on weather data, for example, received by thebuilding management system 34 from a remote data source 66 andcommunicated from the building management system 34 to the scrubbercontrol circuitry 124.

When outside air parameters are determined during the bleed phase, insome embodiments, re-determining the parameters during the cool downphase may be obviated. In any case, as described above, air contaminantsreleased from the contaminant filter may be selectively vented usingeither return air or outside air based at least in part on parameters ofthe outside air. Since the cool down phase follows the bleed phase, thescrubber unit 70 may continue using air received from the venting airsource (e.g., return air duct 28 or outside air duct 76) during the cooldown phase.

In other words, when outside air is used for venting during the bleedphase, the scrubber control circuitry 124 may control operation of thescrubber unit 70 such that the return inlet damper 114 and the returnoutlet damper 116 are maintained in a fully closed position (processblock 242) while the outside inlet damper 118 and the outside outletdamper 120 are both maintained in a partially open position (processblock 244), thereby enabling outside air to continue flowing through thescrubber unit 70 during the cool down phase. For example, during thecool down phase, the scrubber control circuitry 124 may instruct theoutside inlet actuator 94C to transition to and/or maintain the outsideinlet damper 118 at a 60% open position. Additionally, the scrubbercontrol circuitry 124 may instruct the outside outlet actuator 94D totransition to and/or maintain the outside outlet damper 120 at a 60%open position.

On the other hand, when return air is used for venting during the bleedphase, the scrubber control circuitry 124 may control operation of thescrubber unit 70 such that the outside inlet damper 118 and the returnoutlet damper 116 are both maintained in a fully closed position(process block 248) while the return inlet damper 114 and the outsideoutlet damper 120 are both maintained in a partially open position(process block 246), thereby enabling return air to continue flowingthrough the scrubber unit 70 during the cool down phase. For example,during the cool down phase, the scrubber control circuitry 124 mayinstruct the return inlet actuator 94A to transition to and/or maintainthe return inlet damper 114 at a 60% open position. Additionally, thescrubber control circuitry 124 may instruct the outside outlet actuator94D to transition to and/or maintain the outside outlet damper 120 at a60% open position.

To facilitate reducing temperature of the contaminant filter 108, thescrubber control circuitry 124 may also control operation of thescrubber unit 70 such that the closed loop damper 110 is maintained in apartially open position (process block 250), the fan 102 is maintainedon (process block 252), and the heater 104 is maintained off (processblock 254). In this manner, the fan 102 may circulate air (e.g., outsideair or return air) through the scrubber unit 70 without artificiallyincreasing temperature via the heater 104. Since temperature of thecirculated air is generally lower than the target regenerationtemperature of the contaminant filter 108, circulating air through thecontaminant filter 108 may facilitate reducing temperature of thecontaminant filter 108 during the cool down phase.

In some embodiments, the scrubber unit 70 may operate in the cool downphase for a fixed duration. For example, the duration of the cool downphase may be ten minutes. Additionally or alternatively, the scrubberunit 70 may operate in the cool down phase for a variable duration, forexample, until temperature of the contaminant filter 108 is within atarget sorption temperature range. In any case, in this manner, ascrubber unit 70 may operate in a cool down phase of a regeneration modeto facilitate reducing temperature of its contaminant filter 108, whichat least in some instances may reduce duration before the scrubber unit70 is able to operate in the sorption mode.

In this manner, when filtering efficiency is less than a filteringefficiency threshold, the scrubber control circuitry 124 mayautonomously initiate a regeneration cycle by instructing the scrubberunit 70 to operate in a regeneration mode. Additionally oralternatively, the scrubber control circuitry 124 may periodicallyinitiate a regeneration mode, for example, based at least in part onpredetermined schedule. Furthermore, in some embodiments, a regenerationmode may be initiated by a user input, for example, communicated from aclient device 64 to the building management system 34 and from thebuilding management system 34 to the HVAC subsystem 12.

Moreover, as described above, the scrubber control circuitry 124, insome embodiments, may selectively instruct the scrubber unit 70 tooperate in one of multiple regeneration modes (e.g., quick regenerationmode, standard regeneration mode, and extended regeneration mode). Insome embodiments, each of multiple regeneration modes may providediffering tradeoffs between duration a scrubber unit 70 is unavailableto operate in the sorption mode and filtering efficiency provided duringsubsequent operation, for example, due to varying bleed phase durations.Since contaminant level present in return air generally varies at leastin part with number of living beings in the building 10, likelihood thatthe scrubber unit 70 is instructed to operate in the sorption mode mayincrease as occupancy of the building 10 increases. Thus, in someembodiments, the scrubber control circuitry 124 may instruct thescrubber unit 70 to operate in one of the multiple regeneration modesbased at least in part on occupancy status of the building 10.

To help illustrate, an example of a process 256 for selectivelyoperating a scrubber unit in one of multiple regeneration modes isdescribed in FIG. 14. Generally, the process 256 includes determiningoccupancy status of a building (process block 258), determining whetherthe building is currently occupied (decision block 260), and operating ascrubber unit in a quick regeneration mode when the building iscurrently occupied (process block 262). When the building is notcurrently occupied, the process 256 includes determining whetherduration before the building is expected to be occupied is greater thana duration threshold (decision block 264), operating the scrubber unitin a standard regeneration mode when the duration before the building isexpected to be occupied is not greater than the duration threshold(process block 266), and operating the scrubber unit in an extendedregeneration mode when the duration before the building is expected tobe occupied is greater than the duration threshold (process block 268).In some embodiments, the process 256 may be implemented at least in partby executing instructions stored in tangible, non-transitory,computer-readable media, such as memory 140, using processing circuitry,such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine occupancy (e.g., current occupancy and/or expected futureoccupancy) status of a building 10 (process block 258). As describedabove, in some embodiments, a building management system 34 maydetermine occupancy (e.g., state) data indicative of occupancy status ofa building 10. For example, by analyzing image data (e.g., video)captured by the security system 40, the building management system 34may determine current occupancy status of the building 10 and indicatethe current occupancy status via corresponding occupancy data. Thus, insome embodiments, the scrubber control circuitry 124 may determinewhether the building 10 is currently occupied, whether a building zone74 in the building 10 is currently occupied, number of individualscurrently occupying the building 10, number of individuals currentlyoccupying the building zone 74, and/or location of individuals currentlyoccupying the building 10 based at least in part on correspondingoccupancy data.

Additionally, in some embodiments, a building management system 34 maydetermine expected future occupancy status of the building 10. Forexample, by analyzing previous (e.g., historical) occupancy trends, thebuilding management system 34 may predict occupancy of the building 10expected to occur over a prediction horizon (e.g., future time period)and indicated the expected future occupancy status via correspondingoccupancy data. Thus, in some embodiments, the scrubber controlcircuitry 124 may determine an expected occupancy schedule, when thebuilding 10 is expected to be unoccupied, when a building zone 74 in thebuilding 10 is expected to be unoccupied, duration the building 10 isexpected to remain unoccupied, and/or duration the building zone 74 isexpected to remain unoccupied based at least in part on correspondingoccupancy data.

As described above, in some embodiments, a quick regeneration mode, astandard regeneration mode, and an extended regeneration mode may eachinclude a closed loop heating phase, a bleed phase, and a cool downphase. However, each of the regeneration modes may provide differingtradeoffs between duration the scrubber unit 70 is unavailable tooperate in the sorption mode and filtering efficiency available duringsubsequent operation. For example, due to its shorter bleed phase, thequick regeneration mode may facilitate reducing total duration of aregeneration cycle and, thus, duration the scrubber unit 70 isunavailable to operate in the sorption mode compared to the standardregeneration mode and even more so the extended regeneration mode.

Accordingly, when occupancy status is indicative of the building 10being currently occupied, the scrubber control circuitry 124 may controloperation of a scrubber unit 70 such that the scrubber unit 70 operatesin the quick regeneration mode (process block 262). In this manner,filtering efficiency provided by the scrubber unit 70 during subsequentoperation may be improved while reducing duration operation in thesorption mode is unavailable, for example, compared to the standardregeneration mode or the extended regeneration mode. However, due to itslonger bleed phase, the standard regeneration mode may facilitateincreasing amount of previously sorbed air contaminants released fromthe contaminant filter 108 during a regeneration cycle and, thus,subsequent filtering efficiency compared to the quick regeneration mode.Moreover, due to its longer bleed phase, the extended regeneration modemay facilitate increasing amount of previously sorbed air contaminantsreleased from the contaminant filter 108 during a regeneration cycleand, thus, subsequent filtering efficiency compared to the standardregeneration mode.

Accordingly, when occupancy status is indicative of the building 10being currently unoccupied, the scrubber control circuitry 124 maydetermine whether to operate the scrubber unit 70 in the standardregeneration mode or the extended regeneration mode based at least inpart on duration the building is expected to remain unoccupied, forexample, in comparison with a duration threshold (decision block 264).In some embodiments, the duration threshold may be predetermined andstored in a tangible, non-transitory, computer-readable medium, such asmemory 140. Thus, in such embodiments, the scrubber control circuitry124 may retrieve the duration threshold from the tangible,non-transitory, computer-readable medium and compare the expectedunoccupied duration with the duration threshold. Furthermore, in someembodiments, the duration threshold may be set based at least in part ontotal duration of a cycle through the extended regeneration mode, forexample, such that duration threshold is equal to or longer than theduration of an extended regeneration cycle.

Accordingly, when occupancy status is indicative of the building 10remaining unoccupied a duration not greater than the duration threshold,the scrubber control circuitry 124 may determine that there isinsufficient time to complete a cycle through the extended regenerationmode before the building 10 is expected to be occupied and, thus,operate the scrubber unit 70 in the standard regeneration mode (processblock 266). On the other hand, when occupancy status is indicative ofthe building 10 remaining unoccupied a duration greater than theduration threshold, the scrubber control circuitry 124 may determinethat there is sufficient time to complete a cycle through the extendedregeneration mode before the building 10 is expected to be occupied and,thus, operate the scrubber unit 70 in the extended regeneration mode(process block 268). In this manner, a scrubber unit 70 may selectivelyimplement one of multiple regeneration modes based at least in part onoccupancy status of a building 10, for example, to facilitate varyingtradeoff between duration the scrubber unit 70 is unavailable to operatein the sorption mode and filtering efficiency available during asubsequent cycle through the sorption mode.

To facilitate improving operational reliability, in some embodiments,diagnostics may be performed on a scrubber unit 70 based at least inpart on its operation during one or more regeneration cycles. To helpillustrate, an example of a process 270 for performing diagnostics on ascrubber unit 70 is described in FIG. 15. Generally, the process 270includes determining parameters associated with each regeneration cycle(process block 272) and performing diagnostics on a scrubber unit basedat least in part on the parameters (process block 274). In someembodiments, the process 270 may be implemented at least in part byexecuting instructions stored in a tangible, non-transitory,computer-readable medium, such as memory 140, using processingcircuitry, such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine parameters associated with each time a scrubber unit 70 cyclesthrough a regeneration mode (process block 272). In some embodiments,parameters associated with a regeneration cycle may include operationalparameters of the contaminant filter 108, such as filtering efficiencybefore the regeneration cycle and/or filtering efficiency after theregeneration cycle. Additionally, in some embodiments, parametersassociated with a regeneration cycle may include when the regenerationcycle is initiated, when the regeneration cycle is completed, durationof its closed loop heating phase, duration of its bleed phase, durationof its cool down phase, and/or total duration of the regeneration cycle.

To facilitate subsequent analysis, in some embodiments, parametersassociated with a regeneration cycle may be stored in a tangible,non-transitory, computer-readable medium. For example, the scrubbercontrol circuitry 124 may store parameters associated with one or moreregeneration cycles in memory 140. Additionally or alternatively,parameters associated with one or more regeneration cycles may be storedin a remote data source 66, for example, by a building management system34 and/or scrubber control circuitry 124.

By analyzing the regeneration cycle parameters, the scrubber controlcircuitry 124 may perform diagnostics on operation of the scrubber unit70 (process block 274). Thus, when stored in a tangible, non-transitory,computer-readable medium, the scrubber control circuitry 124 mayretrieve parameters associated with one or more regeneration cycles fromthe tangible, non-transitory, computer-readable medium. Additionally, insome embodiments, the scrubber control circuitry 124 may performdiagnostics by analyzing parameter trends. For example, when durationbetween successive quick regeneration cycles trends below a durationthreshold, the scrubber control circuitry 124 may determine thatoperating in the quick regeneration mode insufficiently improvesfiltering efficiency during subsequent operation and, thus, thecontaminant filter 108 should be replaced.

To facilitate improving operational reliability, in some embodiments,the scrubber control circuitry 124 may autonomously adjust operation ofthe scrubber unit 70 based at least in part on the diagnostic results.Additionally or alternatively, the diagnostic results may be presentedto a user (e.g., operator), for example, via a graphical user interfacedisplayed on the electronic display 69 of a client device 64. In thismanner, in addition to controlling operation of a corresponding scrubberunit 70, scrubber control circuitry 124 may facilitate monitoringoperation of the scrubber unit 70.

As described above, in some embodiments, scrubber control circuitry 124may also control operation of other equipment in an HVAC subsystem 12.In fact, in some embodiments, equipment controlled by scrubber controlcircuitry 124 may be external from its corresponding scrubber unit 70.For example, the scrubber control circuitry 124 may control operation ofan outside air damper 78B implemented in an air handling unit of theHVAC subsystem 12.

In some embodiments, the scrubber control circuitry 124 may controloperation of the outside air damper 78B based at least in part onoperational mode of the scrubber unit 70. For example, while operatingin a regeneration mode, a scrubber unit 70 may be unavailable to operatein the sorption mode. Thus, to facilitate producing supply air inaccordance with a target contaminant level, the scrubber controlcircuitry 124 may control operation of the air handling unit 30 suchthat the outside air damper 78B is transitioned to and/or maintained ina fully open position, thereby enabling corresponding air handlercontrol circuitry 86 to control supply air contaminant level byadjusting amount of outside air used to produce the supply air. While inother operating (e.g., standby or sorption) modes, in some embodiments,the scrubber control circuitry 124 may control operation of the outsideair damper 78B based at least in part on parameters of return air and/orparameters of outside air.

To help illustrate, an example of a process 276 for controllingoperation of an outside air damper 78B implemented in an air handlingunit 30 while a corresponding scrubber unit 70 operates in a standbymode is described in FIG. 16. Generally, the process 276 includesdetermining operational status of an air handling unit (process block278), determining whether the operational status of the air handlingunit is on (decision block 280), and maintaining an outside air damperof the air handling unit in a closed position when the air handling unitis not on (process block 282). When the air handling unit is on, theprocess 276 includes determining a parameter of outside air (processblock 284), determining whether the parameter of the outside air iswithin a target range (decision block 286), maintaining the outside airdamper of the air handling unit in a fully open position when theparameter is within the target range (process block 288), andmaintaining the outside air damper of the air handling unit in apartially open position when the parameter is not within the targetrange (process block 290). In some embodiments, the process 276 may beimplemented at least in part by executing instructions stored in atangible, non-transitory, computer-readable medium, such as memory 140,using processing circuitry, such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine operational status of an air handling unit 30, for example,implemented in the same HVAC subsystem 12 as a corresponding scrubberunit 70 (process block 278). As described above, in some embodiments,the scrubber control circuitry 124 may receive an indication ofoperational status and/or other operational parameters associated withan air handling unit 30 from corresponding air handler control circuitry86. Additionally or alternatively, the scrubber control circuitry 124may receive an indication of the operational parameters associated withthe air handling unit 30 from the building management system 34. Forexample, the scrubber control circuitry 124 may determine operationalstatus of an air handling unit 30 based at least in part on receivedparameter (e.g., state) data, which indicates whether the air handlingunit 30 is in an on state or an off state.

When the air handling unit 30 is off, the scrubber control circuitry 124may control operation of the air handling unit 30 such that at least oneof its outside air damper 78B is maintained in a fully closed position(process block 282). For example, the scrubber control circuitry 124 mayinstruct an external actuator 94F to transition to and/or maintain acorresponding outside air damper 78B in a fully closed position. Asdescribed above, in some embodiments, an air handling unit 30 mayinclude multiple outside air dampers 78B. For example, the air handlingunit 30 may include a first outside air damper 78B, which is controlledby its air handler control circuitry 86. To facilitate adapting (e.g.,retrofit) the air handling unit 30 based on the techniques describedherein, in some embodiments, a second outside air damper 78B, which iscontrolled by the scrubber control circuitry 124, may be coupledupstream relative to the first outside air damper 78B. In other words,in such embodiments, the scrubber control circuitry 124 may physicallyoverride the air handler control circuitry 86 since damper position ofthe second outside air damper 78B affects air flow to the first outsideair damper 78B.

Nevertheless, in some embodiments, an air handling unit 30 may beimplemented with a single outside air damper 78B. In such embodiments,the scrubber control circuitry 124 may control operation of the outsideair damper 78B of the air handling unit 30 by digitally overriding theair handler control circuitry 86. For example, the scrubber controlcircuitry 124 may instruct the air handler control circuitry 86 tocontrol damper position of the outside air damper 78B based on a firsttarget outside air damper position determined by the scrubber controlcircuitry 124 instead of a second target outside damper positiondetermined by the air handler control circuitry 86. In any case, bymaintaining at least one outside air damper 78B in an air handling unit30 in a fully closed position, flow of outside air into an internalportion of the air handling unit 30 may be blocked while the airhandling unit 30 is in an off state.

As described above, when an air handling unit 30 is on, a scrubber unit70 may operate in the standby mode while return air contaminant level isnot greater than a contaminant level lower threshold. Thus, when the airhandling unit 30 is on, the scrubber control circuitry 124 may determinesuitability of outside air for use in supply air based at least in parton parameters of the outside air, such as temperature, humidity, and/orcontaminant level (process block 284). As described above, in someembodiments, the scrubber control circuitry 124 may determine parametersof outside air based at least in part on sensor data received from anoutside air sensor 142. Additionally or alternatively, the scrubbercontrol circuitry 124 may determine parameters of outside air based atleast in part on weather data, for example, received by the buildingmanagement system 34 from a remote data source 66 and communicated fromthe building management system 34 to the scrubber control circuitry 124.

In some embodiments, the scrubber control circuitry 124 may determinesuitability of outside air for use in supply air based at least in parton whether outside air parameters are within corresponding target ranges(decision block 286). For example, to reduce likelihood of freezing theair handling unit 30, the scrubber control circuitry 124 comparetemperature of the outside air with a target outside air temperature. Insome embodiments, likelihood of an air handling unit 30 freezing maysubstantially increase when temperature of air flowing through the airhandling unit 30 is below a low temperature threshold. Thus, in suchembodiments, the target outside air temperature may be set based atleast in part on the low temperature threshold, for example, such thatthe target outside air temperature includes a range of temperature at orabove the low temperature threshold.

Accordingly, when an outside air parameter is not within its targetrange, the scrubber control circuitry 124 may determine that outside airis less favorable for use in supply air compared to return air and,thus, control operation of the air handling unit 30 such that the atleast one outside air damper 78B is maintained in a partially openposition (process block 290). In some embodiments, damper position ofthe outside air damper 78B may be controlled based at least in part on atarget standby damper position. For example, the scrubber controlcircuitry 124 may instruct the external actuator 94F to transition toand/or maintain a corresponding outside air damper 78B at a 10% (e.g.,minimum) open position, thereby limiting flow of outside air into theair handling unit 30. At least in some instance, this may facilitateimproving operational reliability of an air handling unit 30, forexample, by reducing likelihood of cold outside air freezing equipmentin the air handling unit 30.

On the other hand, when each outside air parameter is within its targetrange, the scrubber control circuitry 124 may determine that outside airfavorable for use in supply air and, thus, control operation of the airhandling unit 30 such that the at least one outside air damper 78B ismaintained in a fully open position (process block 288). For example,the scrubber control circuitry 124 may instruct an external actuator 94Fto transition to and/or maintain a corresponding outside air damper 78Bin the fully open position. By maintaining the outside air damper 78B inthe fully open, the scrubber control circuitry 124 may enable airhandler control circuitry 86 corresponding with the air handling unit 30to control supply air contaminant level by adjusting amount of outsideair used to produce the supply air.

In this manner, while a corresponding scrubber unit 70 operates in thestandby mode, scrubber control circuitry 124 may control operation of anair handling unit 30 based at least in part on operational status of theair handling unit 30 and parameters of outside air, which may be drawninto the air handling unit 30. As described above, in some embodiments,scrubber control circuitry 124 may additionally or alternatively controloperation of an air handling unit 30 based at least in part onparameters of return air. For example, while a corresponding scrubberunit 70 operate in the sorption mode, the scrubber control circuitry 124may control operation of the air handling unit 30 based at least in parton parameters of return air flowing through the scrubber unit 70.

To help illustrate, an example of a process 292 for controllingoperation of an outside air damper 78B implemented in an air handlingunit 30 while a corresponding scrubber unit 70 operates in a sorptionmode is described in FIG. 17. Generally, the process 292 includesdetermining contaminant level in return air (process block 294),determining whether the contaminant level is greater than an upperthreshold (decision block 296), maintaining an outside air damper of anair handling unit in a partially open position when the contaminantlevel is not greater than the upper threshold (process block 298), andmodulating the outside air damper of the air handling unit above thepartially open position when the contaminant level is greater than theupper threshold (process block 300). In some embodiments, the process292 may be implemented by executing instruction stored in a tangible,non-transitory, computer-readable medium, such as memory 140, usingprocessing circuitry, such as processor 138.

Accordingly, in some embodiments, scrubber control circuitry 124 maydetermine contaminant level present in return air (process block 156).As described above, in some embodiments, a scrubber unit 70 may includea return inlet sensor 92A coupled on its return inlet damper 114 and/ora return outlet sensor 92B coupled on its return outlet damper 116. Insuch embodiments, the scrubber control circuitry 124 may determinecontaminant level present in return air based at least in part on sensordata received from the return inlet sensor 92A and/or sensor datareceived from the return outlet sensors 92B.

As described above, in some embodiments, operation of a scrubber unit 70in the sorption mode may be initiated (e.g., triggered) when return aircontaminant level exceeds a contaminant level upper threshold. Whileoperating in the sorption mode, the scrubber unit 70 may facilitatereducing contaminant level present in return air by actively introducinga pressure differential across its contaminant filter 108. As describedabove, when the pressure differential is within a target regenerationpressure range, chemical compounds in the contaminant filter may undergoa chemical reaction that sorbs (e.g., absorbs or adsorbs) aircontaminants from return air flowing through the scrubber unit 70.

Accordingly, when return air contaminant level is able to be reducedbelow the contaminant level upper threshold, the scrubber controlcircuitry 124 may determine that operating the scrubber unit 70 in thesorption mode sufficiently reduces the contaminant level and, thus,control operation of the air handling unit 30 such that its outside airdamper 78B is maintained in a partially open position (process block298). In some embodiments, damper position of the outside air damper 78Bmay be controlled based at least in part on a target sorption damperposition. For example, the scrubber control circuitry 124 may instructthe external actuator 94F to transition to and/or maintain acorresponding outside air damper 78B at a 10% (e.g., minimum) openposition, thereby limiting flow of outside air into an internal portionof the air handling unit 30. At least in some instance, this mayfacilitate improving operational efficiency of an air handling unit 30and, thus, an HVAC subsystem 12, for example, by enabling the airhandling unit 30 to produce supply air using more return air and/or lessoutside air.

On the other hand, when return air contaminant level remains above thecontaminant level upper threshold, the scrubber control circuitry 124may determine that operating the scrubber unit 70 in the sorption modeinsufficiently reduces the contaminant level. Thus, to facilitateproducing supply air that meets a target contaminant level, the scrubbercontrol circuitry 124 may control operation of the air handling unit 30such that the outside air damper 78B is modulated above the partiallyopen position (process block 300). For example, when return aircontaminant level is above the contaminant level upper threshold, thescrubber control circuitry 124 may instruct the external actuator 94F totransition the corresponding outside air damper 78B from a 10% (e.g.,partially) open position to a 15% open position. Additionally, if thereturn air contaminant level continues to remain above the contaminantlevel upper threshold, the scrubber control circuitry 124 may instructthe external actuator 94F to transition the corresponding outside airdamper 78B from the 15% open position to a 20% open position.

As open position increases, limitation on air flow due to damperposition of the outside air damper 78B may be reduced, therebyincreasing amount of outside air available to the air handling unit 30for producing supply air. In other words, by modulating the outside airdamper 78B above the partially open position, the scrubber controlcircuitry 124 may supplement the contaminant level reduction provided bythe scrubber unit 70. As described above, in some embodiments,contaminant level reduction provided by a scrubber unit 70 may belimited by filtering efficiency of its contaminant filter 108.Additionally, in some embodiments, filtering efficiency of a contaminantfilter 108 and, thus, provided contaminant level reduction may graduallychange (e.g., decrease) over time. Moreover, contaminant level presentin return air may vary over time, for example, based at least in part onoccupancy. By controlling operation of an air handling unit 30 in thismanner, scrubber control circuitry 124 may facilitate improvingoperational reliability of an HVAC subsystem 12, for example, byaccounting for changes over time to facilitate producing supply air thatmeets a target contaminant level.

To facilitate further improving operational reliability, in someembodiments, information related to operation of an HVAC subsystem 12and/or other building subsystems may be communicated to a user (e.g.,operator). For example, when a fault (e.g., fire) condition is detectedin a scrubber unit 70, corresponding scrubber control circuitry 124 maycontrol operation of the scrubber unit 70 such that its heater 104 ismaintained off, its fan 102 is maintained off, its return inlet damper114 is maintained in a fully closed position, its return outlet damper116 is maintained in a fully closed position, its outside inlet damper118 is maintained in a fully closed position, its outside outlet damper120 is maintained in a fully closed position, and its closed loop damper110 is maintained in a fully closed position, which at least in someinstances may reduce likelihood of the fault condition spreading toother portions of the HVAC subsystem 12. Additionally or alternatively,the scrubber control circuitry 124 may facilitate alerting a user (e.g.,operator) to the fault condition, for example, by communicating anindication of the fault condition to a building management system 34 toenable the building management system 34 to generate an audio alarmand/or a visual alarm.

To facilitate communicating a visual alarm and/or other visualrepresentations of information related to operation, in someembodiments, a building management system 34 may generate a graphicaluser interface (GUI) for display via an electronic display 69, forexample, implemented on a client device 64 communicatively coupled tothe building management system 34. To help illustrate, examples ofgraphical user interfaces 302, which may be generated by a buildingmanagement system 34, are shown in FIGS. 17 and 18. In particular, afirst graphical user interface 302A is shown in FIG. 17 and a secondgraphical user interface 302B is shown in FIG. 18. It should beappreciated that the example graphical user interfaces are merelyintended to be illustrative and not limiting. For example, in otherembodiments, the building management system 34 may generate a graphicaluser interface 302 that additionally or alternatively includes a visualrepresentation of information related to a building subsystem other thanan HVAC subsystem 12.

In any case, with regard to FIG. 17, the first graphical user interface302A includes a list portion 304 and a graphics portion 306. In someembodiments, the list portion 304 may include multiple entries listedbased at least in part on hierarchal organization. For example, in thedepicted example, the list portion 304 is organized by campus (e.g.,site), building management systems 34 associated with each campus,buildings 10 implemented with subsystems controlled by each buildingmanagement system 34, and equipment (e.g., variable air volume units 32,air handling units 30, and/or scrubber units 70) implemented in eachbuilding 10.

Additionally, in some embodiments, the graphics portion 306 may begenerated based at least in part on selections made in the list portion304, for example, by user inputs received via input devices 68 on aclient device 64. In the depicted example, the graphics portion 306includes a visual representation of information related to a scrubberunit 70 since an entry corresponding with the scrubber unit 70 isselected in the list portion 304. Since a campus may include multiplebuildings 10, in some embodiments, the graphics portion 306 may includea visual representation of the building 10 served by equipmentcorresponding with the selected entry to facilitate indicating locationof the equipment. In the depicted example, the graphics portion 306displays a visual representation of building one (e.g., as captured by acamera) since the scrubber unit 70 corresponding with the selected entryserves building one.

Since a building 10 may include multiple different types of equipment,in some embodiments, the graphics portion 306 may include a visualrepresentation of the equipment corresponding with a selected entry. Inthe depicted example, since the selected entry corresponds with ascrubber unit 70, the graphics portion 306 includes a visualrepresentation of the scrubber unit 70, for example, as captured by acamera. In fact, in the depicted example, the visual representation ofthe scrubber unit 70 is superimposed on the visual representation ofbuilding one such that the scrubber unit 70 appears to be implemented ina room adjacent building one and building one is visible through awindow in the room. In this manner, a graphics portion 306 of agraphical user interface 302 may facilitate communicating information,such as served building 10 and/or type of corresponding equipment,related to a selected entry.

Moreover, in some embodiments, the graphics portion 306 may includevisual representations of operational parameters of equipmentcorresponding with a selected entry. In the depicted example, thegraphics portion 306 includes a visual representation of outside airparameters, return air parameters determined via a return inlet sensor92A, return air parameters determined via a return outlet sensor 92B,parameters of a contaminant filter 108, and operational mode of thescrubber unit 70. To facilitate improving control transparency, in someembodiments, a building management system 34 may generate a graphicaluser interface including additional information based at least in parton user interaction with the graphics portion 306.

For example, the building management system 34 may generate the secondgraphical user interface 302B shown in FIG. 18 when a user input selectsthe visual representation of the inlet return air parameters, the visualrepresentation of the outlet return air parameters, or the visualpresentation of the contaminant filter parameters. In any case, in thedepicted example, the second graphical user interface 302B includes aplot of inlet return air parameters and outlet return air parameters. Inparticular, the plot includes a first curve 308, which indicatescontaminant level of inlet return air over an approximately twenty-fourhour period (e.g., 7:10 AM on a first day to 6:50 AM on a second day),and a second curve 310, which indicates contaminant level of outletreturn air over the approximately twenty-four hour period.

In the depicted example, at the beginning of the twenty-four hourperiod, the outlet contaminant level is substantially lower than theinlet contaminant level, for example, due to previously completing anextended regeneration cycle. However, as the contaminant filter 108continues to sorb air contaminants, the outlet contaminant levelgradually increases. By approximately 12:30 PM, filtering efficiency(e.g., (inlet contaminant level−outlet contaminant level)/inletcontaminant level) may be reduced below an efficiency threshold, therebytriggering a first quick regeneration cycle.

In the depicted example, the first quick regeneration cycle is completedby approximately 1:30 PM and, thus, subsequent outlet contaminant levelis substantially lower than the outlet contaminant level immediatelybefore the first quick regeneration cycle even though the inletcontaminant level is approximately the same. As filtering efficiencyagain gradually decreases, by approximately 3:50 PM, filteringefficiency may be reduced below the efficiency threshold, therebytriggering a second quick regeneration cycle. In the depicted example,the second regeneration cycle is completed by approximately 4:50 PM and,thus, subsequent outlet contaminant level is substantially lower thanthe outlet contaminant level immediately before the second quickregeneration cycle.

Although outlet contaminant level may vary over time, as illustrated bythe depicted example, operating a scrubber unit 70 utilizing thetechniques described herein (e.g., the sorption mode) generallyfacilitates maintaining outlet contaminant level lower than inletcontaminant level. In some embodiments, sensor data received from areturn outlet sensor 92B may indicate a spike in outlet contaminantlevel during a (e.g., second quick) regeneration cycle, for example, dueto the return outlet sensor 92B determining contaminant level while thecontaminant filter 108 is releasing previously sorbed air contaminants.However, by maintaining in a fully closed position during theregeneration cycle, the return outlet damper 116 may block flow of thereleased air contaminants from recombining with return air.

In other words, controlling operation of a scrubber unit 70 utilizingthe techniques described herein may facilitate reducing contaminantlevel present in return air, for example, by sorbing air contaminantsfrom return air flowing through the scrubber unit 70. As describedabove, reducing contaminant level present in return air may enable anair handling unit 30 to produce supply air using more of the return airand/or less outside air, which at least in some instances may facilitatereducing power consumption and, thus, improving operational efficiencyof an HVAC subsystem 12 including the air handling unit 30. Tofacilitate further improving effectiveness of the control techniques,the present disclosure additionally provides techniques for implementing(e.g., designing and/or manufacturing) a scrubber unit 70.

To help illustrate, a perspective view of an example scrubber unit 70Ais shown in FIG. 20. It should be noted that, although not depicted inFIG. 20, the scrubber unit 70A may include additional components. Forexample, as will be described in more detail below, the scrubber unit70A may additionally include one or more doors or door panels that coverthe front (e.g., open) side of the scrubber unit 70A.

In the depicted example, the scrubber unit 70A includes a housing 100formed by at least a side panel 311, a top panel 313, and a bottom panel315. The housing 100 encloses an internal portion of the scrubber unit70A, which includes two fans 102, a heater 104, a flame shield 106, acontaminant filter 108, a closed loop damper 110, and a particle filter112. In the depicted example, the contaminant filter 108 is implementedusing a set of multiple (e.g., twelve) filter cartridges 312 and thefans 102 are mounted in a fan panel 314, which extends in a first (e.g.,horizontal) direction 322 and a second (e.g., outwardly) direction 324.Additionally, the heater 104 and the flame shield 106 are disposedbetween the fans 102 and the contaminant filter 108.

Furthermore, in the depicted example, the scrubber unit 70A includes areturn inlet damper 114 and an outside inlet damper 118 each implementedin a corresponding opening formed in the side panel 311. The scrubberunit 70A also includes a return outlet damper 116 and an outside outletdamper 120 each implemented in a corresponding opening formed in the toppanel 313. To facilitate adjusting damper position, the scrubber unit70A includes a return inlet actuator 94A mechanically coupled to thereturn inlet damper 114, a return outlet actuator 94B mechanicallycoupled to the return outlet damper 116, an outside inlet actuator 94Cmechanically coupled to the outside inlet damper 118, and an outsideoutlet actuator 94D mechanically coupled to the outside outlet damper120. Similarly, to facilitate adjusting damper position of the closedloop damper 110, the scrubber unit 70A includes a closed loop actuator94E mechanically coupled to the closed loop damper 110, for example,through an opening in the top panel 313.

A control panel 122 corresponding with the scrubber unit 70A is alsoimplemented in an opening formed in the side panel 311. As describedabove, in some embodiments, the control panel 122 may include scrubbercontrol circuitry 124 that controls operation of the scrubber unit 70A.For example, to facilitate controlling flow rate and/or source of airflowing into the internal portion of the scrubber unit 70A, the scrubbercontrol circuitry 124 may instruct the return inlet actuator 94A toadjust damper position of the return inlet damper 114 and/or instructthe outside inlet actuator 94C to adjust damper position of the outsideinlet damper 118. Additionally, to facilitate controlling flow rateand/or sink of air flowing out from the internal portion of the scrubberunit 70A, the scrubber control circuitry 124 may instruct the returnoutlet actuator 94B to adjust damper position of the return outletdamper 116 and/or instruct the outside outlet actuator 94D to adjustdamper position of the outside outlet damper 120.

Furthermore, in some embodiments, the scrubber control circuitry 124 mayinstruct the closed loop actuator 94E to adjust damper position of theclosed loop damper 110 to facilitate controlling flow of air within theinternal portion of the scrubber unit 70A. In some embodiments, theinternal portion of a scrubber unit 70A may be divided into multiplesegments 316 (e.g., portions or compartments) by one or morecross-members 318. For example, in the depicted example, a firstcross-member 318A separates a first (e.g., upper) segment 316A and asecond (e.g., middle) segment 316B. Additionally, a second cross-member318B separates the second segment 316B and a third (e.g., lower) segment316C. Furthermore, in the depicted example, the closed loop damper 110is implemented in an opening formed in an internal panel 320, which iscoupled to the fan panel 314 in the third segment 316C and extends in athird (e.g., vertical) direction 326 through the first segment 316A andthe second segment 316B.

A more detailed view of a portion of the scrubber unit 70A around thejunction between the internal panel 320 and the second cross-member 318Bis shown in FIG. 21. In the depicted example, the internal panel 320extends transverse to the second cross-member 318B, which at least insome instance may facilitate shielding the set of filter cartridges 312,the fans 102, the flame shield 106, and heater 104 implemented on oneside of the internal panel 320 from the control panel 122 implemented onthe opposite side of the internal panel 320. Additionally, the set offilter cartridges 312 may be coupled between cartridge decks 328.

To help illustrate, a side view of the filter cartridges 312 coupledbetween a bottom cartridge deck 328A and a top cartridge deck 328B isshown in FIG. 22. As depicted, the bottom cartridge deck 328A includes adeck lip 329 formed on either side. In some embodiments, each deck lip329 may extend along the length of a corresponding side of the bottomcartridge deck 328A (e.g., into the page). Additionally, each deck lip329 may be implemented to slidably engage a rack implemented in thescrubber unit 70A.

For example, returning to FIG. 21, a rack 330 is implemented along theinternal panel 320. In some embodiments, the rack 330 may extend alongthe internal panel 320, for example, in the second direction 324.Another rack 330 may similarly be formed along an inner surface of aside panel 311 of the scrubber unit 70A opposite the internal panel 320.By implementing in this manner, the filter cartridges 312 may be movedas a unit (e.g., single group), which at least in some instances mayfacilitate improving serviceability of the filter cartridges 312, forexample, by enabling the set of filter cartridges 312 to be partially oreven fully removed from the internal portion of the scrubber unit 70A asa unit.

In some embodiments, filtering efficiency may be improved by angling thefilter cartridges 312 relative to one another. In other words, in suchembodiments, filtering efficiency may be affected by deformation (e.g.,sagging) of the cartridge decks 328, for example, due to weight of thefilter cartridges 312. To reduce likelihood of such deformation, thecartridge decks 328 may be fixedly coupled to the cross-members 318. Asdepicted, the bottom cartridge deck 328A is fixedly coupled to thesecond cross-member 318B, for example, via a bolt 331 or other couplingmeans. In a similar manner, the top cartridge deck 328B may beadditionally or alternatively coupled to the first cross-member 318A.Thus, when removably coupled to the scrubber unit 70A, the cross-members318 along with the cartridge decks 318 and the filter cartridges 312 maybe moved as a unit.

To facilitate further improving serviceability, in some embodiments,doors or door panels may be disposed on either side of the illustratedcross-member 318. To help illustrate, an example of a door system 332,which may be used to at least partially cover openings in the scrubberunit 70A, is shown in FIG. 23. In the depicted example, the door system332 includes a first (e.g., upper) door 334, a second (e.g., middle)door 336, and a third (e.g., lower) door 338. In some embodiments, thefirst door 334 may correspond with the first segment 316A, the seconddoor 336 may correspond with the second segment 316B, and the third door338 may correspond with the third segment 316C. By implementing in thismanner, each segment 316 may be relatively independently serviced byremoving a corresponding door, for example, while the others remaincoupled to the housing 100 and/or the cross-members 318.

In any case, in the depicted example, the first door 334, the seconddoor 336, and the third door 338 each includes multiple wing latches340, which may facilitate securing a corresponding door to the scrubberunit 70A by interfacing with a structural panel (e.g., side panel 311)of the scrubber unit 70A. In some embodiments, a wing latch 340 may berotatable with respect to its corresponding door. For example, a winglatch 340 may engage the structural panel when rotated a quarter turnone direction and disengage the structural panel when rotated a quarterturn the opposite direction.

In some embodiments, one or more of the doors may include a lock-in tab.To help illustrate, a side view of the first door 334 including alock-in tab 342 is shown in FIG. 24. In some embodiments, a lock-in tab342 may extend along the length of a corresponding door (e.g., into thepage). Thus, the lock-in tab 342 may engage a structure of the scrubberunit 70A, such as a cross-member 318, to facilitate positioning thefirst door 334 appropriately before the first door is secured in place,for example, via corresponding wing latches 340.

Returning to FIG. 23, in the depicted example, the first door 334, thesecond door 336, and the third door 338 each includes at least onerecessed handle 344. In some embodiments, a recessed handle 344 mayfacilitate physically moving a corresponding door, for example, byenabling a user (e.g., operator or technician) to grip and/or pull thedoor. In the depicted example, the second door 336 additionally includestwo thumb latches 346, which at least in some instances may facilitateimproving serviceability of the scrubber unit 70A, for example, byenabling quick locking and/or unlocking of the second door 336. Forexample, when each wing latches 340 implemented on the second door 336is rotated to an unlocked position, the second door 336 may be removedby pressing down on both of the thumb latches 346.

A more detailed view of the fan system 348 implemented in the scrubberunit 70A is shown in FIG. 25. In depicted example, the fan system 348includes a first fan 102A, a second fan 102B, and the fan panel 314(e.g., fan wall or main wall). In particular, the fan panel 314 includea first opening 350A implemented to receive the first fan 102 and asecond opening 350B implemented to receive the second fan 102. Tofacilitate securing the fans 102, the fan panel 314 also includes anumber of mounting holes 352 surrounding the first opening 350A and thesecond opening 350B. In the depicted example, four mounting holes 352surround the first opening 350A and four mounting holes 352 surround thesecond opening 350B. However, in some embodiments, more or fewermounting holes 352 may be formed around an opening 350 in the fan panel314.

Each mounting hole 352 is may receive a nut blind insert 354.Additionally, each nut blind insert 354 may receive a nut blind screw356 that also extends through an opening in the corresponding first fan102 or the second fan 102. In other words, the nut blind screws 356 mayextend through features of the fan panel 314 and engage the nut blindinserts 354 in order to mount the fans 102 in the corresponding openings350 of the fan panel 314. In fact, the illustrated assembly may enablemounting of the fans 102 in the openings 350 without having to tightenscrews in an area of the scrubber unit 70A having low or insufficientclearance, which at least in some instances facilitates improvingserviceability of the fan system 348. However, other fasteningassemblies are also possible.

An example of a frame 357, which may be implemented to mount a controlpanel 122 on a scrubber unit 70A, is shown in FIG. 26. In the depictedexample, the frame 357 includes a first side wall 358, a second sidewall 360, a bottom wall 362, a top wall 364, and a back wall 366. Insome embodiments, the frame 357 may be implemented by wrapping a singlesheet of material (e.g., metal), which may facilitate reducingimplementation associated cost, such as manufacturing steps used to formthe frame 357. In any case, the bottom wall 362 includes lower wire feedholes 368A and the top wall 364 includes upper wire feed holes 368B. Thelower wire feed holes 368A and upper wire feed holes 368B may be punchedthrough the corresponding bottom wall 362 and top wall 364. In otherwords, the bottom wall 362 and the top wall 364 may be implemented toenable passage of wires 141 through the feed holes 368 punchedtherethrough, for example, without using separate wire feed plates,which at least in some instances may facilitate reducing implementationassociated cost of a scrubber unit 70A.

A more detailed view of the top panel 313 of the scrubber unit 70A isshown in FIG. 27. As depicted, the top panel 313 includes the returnoutlet damper 116 and the outside outlet damper 120 mounted thereon.Additionally, the top panel 313 includes eyelet assemblies 369, oneadjacent each corner of the top panel 313. In some embodiments, theeyelet assemblies 369 may be gripped in order to lift the scrubber unit70A upwardly and/or the top panel 313 upwardly away from the scrubberunit 70A, for example, when the top panel 313 is not engaged with otherpanels or structures of the scrubber unit 70A.

A more detailed view of a portion of the top panel 313 including aneyelet assembly 369 is shown in FIG. 28. As depicted, the eyeletassembly 369 includes a lifting eyelet 370, a nut insert 374, a backingplate 376, and a locking nut 380. In some embodiments, the nut insert374 may extend from a top surface of the top panel 313 through anopening 372 to engage the backing plate 376 on a bottom surface of thetop panel 313 (e.g., as indicated by dashed line 378). Additionally, thenut insert 374 may receive the locking nut 380 and the lifting eyelet370. In some embodiments, height of the lifting eyelet 370 relative tothe top panel 313 may be adjustable, for example, by turning the liftingeyelet 370 to adjust position of its shaft within the nut insert 374. Insome embodiments, adjustable height of lifting eyelets 370 mayfacilitate accounting for height differences across the top panel 313,which at least in some instances may facilitate improving serviceabilityof the scrubber unit 70A.

To reduce likelihood of subsequent movement relative to the top panel313, the locking nut 380 may secure the lifting eyelet 370 within thenut insert 374. For example, once positioned at a target height, thelifting eyelet 370 may be secured in place by tightening the locking nut380. In some embodiments, the lifting eyelet 370 may be welded toimprove a coupling between the lifting eyelet 370 and the top panel 313.Additionally or alternatively, the locking nut 380 may be welded in thenut insert 374.

A more detailed view of a damper assembly 383 is shown in FIG. 29. Inthe depicted example, the damper assembly 383 includes an actuator 94coupled via a mounting assembly 386 to an air damper 384. The air damper384 may be implemented as any of a return inlet damper 114, a returnoutlet damper 116, an outside inlet damper 118, or an outside outletdamper 120 on the scrubber unit 70A.

A more detailed view of the mounting assembly 386 is shown in FIG. 30.As depicted, the mounting assembly 386 includes a mounting bracket 387and an actuator lock strap 390 with an upwardly extending engagementfeature 392. In some embodiments, the engagement feature 392 maydirectly engage an actuator 94, for example, at a corresponding opening.Additionally, the actuator lock strap 390 may be secured to the mountingbracket 387 via screws 394. By implementing in this manner, the airdamper 384, the mounting bracket 386, and the actuator 94 may beassembled prior to installation on the scrubber unit 70A, which at leastin some instances may facilitate improving implementation of thescrubber unit 70A.

To help illustrate, an example of the air damper 384 installed in theside panel 311 is shown in FIG. 31. As depicted, a spin ring 388 isinstalled within an opening 396 formed in the side panel 311.Additionally, the air damper 384 extends into and is secured within thespin ring 388 via self-tapping screws 398, which extend through the spinring 388 to an inner surface 400 of the air damper 384. In other words,the air damper 384 may be fixedly coupled with the spin ring 388. A moredetailed view of the spin ring 388 is shown in FIG. 32. In someembodiments, the spin ring 388 may be implemented to be capable ofspinning within the opening 396 of the side panel 311.

A more detailed view of the bottom panel 315 of the scrubber unit 70A isshown in FIG. 32. As depicted, the bottom panel 315 includes footassemblies 402, one adjacent each corner of the bottom panel 315. Tohelp illustrate, a more detailed view of a foot assembly 402 is shown inFIG. 34. As depicted, the foot assembly 403 includes a self-levelingfoot 404, a backing plate 406, and a nut insert 408. In someembodiments, the nut insert 408 may extend from a bottom surface of thebottom panel 315 through an opening (hidden from view) to engage thebacking plate 406 on a top surface of the bottom panel 315 (e.g., asindicated by dashed line 410).

Additionally, the nut insert 408 may receive a shaft of theself-leveling foot 404 to secure the self-leveling foot 404 to thebottom panel 315. In some embodiments, the self-leveling foot 404 may bespring-loaded or otherwise self-leveling to facilitate leveling thescrubber unit 70A. At least in some instances, implementing footassemblies 402 in this manner may facilitate improving deployment of thescrubber unit 70A, for example, when deployed on an uneven surfaceand/or weight of the scrubber unit 70A is unevenly distributed acrossthe bottom panel 315.

One or more of the disclosed embodiments, alone or in combination, mayprovide one or more technical effects useful in enhancing efficiency ofa heat exchanger of an HVAC system. The above-described contaminantscrubber features facilitate improved assembly manufacturing, ease ofaccess for maintenance purposes, and/or enhanced performance. Forexample, the top panel/wall having eyelet lifters, the bottom panel/wallhaving self-leveling feet, and the blind nut inserts/screws of the fanassembly facilitates improved assembly and manufacturing of thecontaminant scrubber. Further, the compartmentalizing of the contaminantscrubber, and removable nature of the cartridge set, facilitates ease ofaccess for maintaining the contaminant scrubber. Further still, thecartridge set structure enables an increased number of cartridges, whichenhances contaminant removal.

While only certain features and embodiments of the present disclosurehave been illustrated and described, many modifications and changes mayoccur to those skilled in the art (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters (e.g., temperatures, pressures, etc.), mountingarrangements, use of materials, colors, orientations, etc.) withoutmaterially departing from the novel teachings and advantages of thesubject matter recited in the claims. The order or sequence of anyprocess or method steps may be varied or re-sequenced according toalternative embodiments. It is, therefore, to be understood that theappended claims are intended to cover all such modifications and changesas fall within the true spirit of the disclosure. Furthermore, in aneffort to provide a concise description of the exemplary embodiments,all features of an actual implementation may not have been described(i.e., those unrelated to the presently contemplated best mode ofcarrying out an embodiment, or those unrelated to enabling the claimedembodiments). It should be appreciated that in the development of anysuch actual implementation, as in any engineering or design project,numerous implementation specific decisions may be made. Such adevelopment effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure, without undue experimentation.

The invention claimed is:
 1. A scrubber unit configured to beimplemented in a heating, ventilation, and air conditioning system,wherein the scrubber unit comprises: a first internal segmentimplemented between a first cross-member and a second cross-member,wherein the first internal segment comprises a contaminant filter; asecond internal segment implemented between the second cross-member anda bottom panel of the scrubber unit, wherein the second internal segmentcomprises a fan and a heater implemented between the fan and thecontaminant filter; a third internal segment implemented between thefirst cross-member and a top panel of the scrubber unit, wherein thethird internal segment comprises a closed loop damper fluidly coupledbetween a first outlet damper coupled to the top panel of the scrubberunit and a first inlet damper coupled to a sidewall of the scrubberunit; and a control panel coupled to the sidewall of the scrubber unit,wherein the control panel comprises control circuitry is programmed to:determine filtering efficiency of the contaminant filter based at leastin part on input contaminant level measured at the first inlet damperand output contaminant level measured at the first outlet damper; andinstruct the scrubber unit to operate in a first regeneration mode whenthe filtering efficiency of the contaminant filter falls below anefficiency threshold to facilitate improving the filtering efficiencyavailable during subsequent operation of the scrubber unit.
 2. Thescrubber unit of claim 1, wherein, to instruct the scrubber unit tooperate in the first regeneration mode, the control circuitry isprogrammed to: instruct a first outlet actuator to maintain the firstoutlet damper in a fully closed position; and instruct a first inletactuator to ramp damper position of the first inlet damper from thefully closed position to a partially open position during a bleed phaseof the first regeneration mode to enable venting air contaminantsreleased from the contaminant filter using return air when: temperatureof outside air is less than a low temperature threshold; humidity of theoutside air is less than a low humidity threshold; humidity of theoutside air is greater than a high humidity threshold; or anycombination thereof.
 3. The scrubber unit of claim 2, wherein, toinstruct the first inlet actuator to ramp damper position of the firstinlet damper, the control circuitry is programmed to: instruct the firstinlet actuator to maintain the first inlet damper at a 10% open positionduring a first duration in the bleed phase of the first regenerationmode; and instruct the first inlet actuator to maintain the first inletdamper at a 20% open position during a second duration in the bleedphase after the first duration; instruct the first inlet actuator tomaintain the first inlet damper at a 30% open position during a thirdduration in the bleed phase after the second duration; instruct thefirst inlet actuator to maintain the first inlet damper at a 40% openposition during a fourth duration in the bleed phase after the thirdduration; and instruct the first inlet actuator to maintain the firstinlet damper at a 50% open position during a fifth duration in the bleedphase after the fourth duration.
 4. The scrubber unit of claim 2,wherein, to instruct the scrubber unit to operate in the firstregeneration mode, the control circuitry is programmed to, whentemperature of the outside air is not less than the low temperaturethreshold, humidity of the outside air is not less than the low humiditythreshold, and humidity of the outside air is not greater than the highhumidity threshold: instruct the first inlet actuator to maintain thefirst inlet damper in the fully closed position during the bleed phaseof the first regeneration mode; and instruct a second inlet actuator toramp a second inlet damper coupled to the sidewall of the scrubber unitfrom the fully closed position to the partially open position during thebleed phase of the first regeneration mode to enable venting the aircontaminants released from the contaminant filter using the outside air.5. The scrubber unit of claim 4, wherein, to instruct the second inletactuator to ramp damper position of the second inlet damper, the controlcircuitry is programmed to: instruct the second inlet actuator tomaintain the second inlet damper at a 10% open position during a firstduration in the bleed phase of the first regeneration mode; and instructthe second inlet actuator to maintain the second inlet damper at a 20%open position during a second duration in the bleed phase after thefirst duration; instruct the second inlet actuator to maintain thesecond inlet damper at a 30% open position during a third duration inthe bleed phase after the second duration; instruct the second inletactuator to maintain the second inlet damper at a 40% open positionduring a fourth duration in the bleed phase after the third duration;and instruct the second inlet actuator to maintain the second inletdamper at a 50% open position during a fifth duration in the bleed phaseafter the fourth duration.
 6. The scrubber unit of claim 1, wherein thecontrol circuitry is programmed to: determine occupancy status of abuilding serviced by the scrubber unit; and instruct the scrubber unitto operate in a second regeneration mode when the occupancy statusindicates that the building is currently unoccupied, wherein duration ofa bleed phase in the second regeneration mode is greater than durationof the bleed phase in the first regeneration mode.
 7. The scrubber unitof claim 6, wherein the control circuitry is programmed to instruct thescrubber unit to operate in a third regeneration mode when the occupancystatus indicates that the building is currently unoccupied and expectedto remain unoccupied a duration greater than a duration threshold,wherein duration of the bleed phase in the third regeneration mode isgreater than duration of the bleed phase in the second regenerationmode.
 8. The scrubber unit of claim 1, wherein, to instruct the scrubberunit to operate in the first regeneration mode, the control circuitry isprogrammed to: instruct a closed loop actuator to adjust damper positionof the closed loop damper from a fully open position to a firstpartially open position; instruct the closed loop actuator to maintaindamper position of the closed loop damper at the first partially openposition during a first duration in a bleed phase of the firstregeneration mode; instruct the closed loop actuator to adjust damperposition of the closed loop damper from the first partially openposition to a second partially open position; and instruct the closedloop actuator to maintain damper position of the closed loop damper atthe second partially open position during a second duration in the bleedphase after the first duration.
 9. The scrubber unit of claim 1,wherein, to instruct the scrubber unit to operate in the firstregeneration mode, the control circuitry is programmed to: instruct aclosed loop actuator to maintain the closed loop damper at a 90% openposition during a first duration in a bleed phase of the firstregeneration mode; and instruct the closed loop actuator to maintain theclosed loop damper at a 80% open position during a second duration inthe bleed phase after the first duration; instruct the closed loopactuator to maintain the closed loop damper at a 70% open positionduring a third duration in the bleed phase after the second duration;instruct the closed loop actuator to maintain the closed loop damper ata 60% open position during a fourth duration in the bleed phase afterthe third duration; and instruct the closed loop actuator to maintainthe closed loop damper at a 50% open position during a fifth duration inthe bleed phase after the fourth duration.
 10. The scrubber unit ofclaim 1, wherein, to instruct the scrubber unit to operate in the firstregeneration mode, the control circuitry is programmed to: instruct aninlet actuator to ramp damper position of the first inlet damper or asecond inlet damper coupled to the sidewall of the scrubber unit from afully closed position to a partially open position during a bleed phaseof the first regeneration mode; and instruct an outlet actuator to rampdamper position of a second outlet damper coupled to the top panel ofthe scrubber unit from the fully closed position to the partially openposition during the bleed phase of the first regeneration mode incoordination with the inlet actuator.
 11. The scrubber unit of claim 10,wherein, to instruct the outlet actuator to ramp damper position of thesecond outlet damper, the control circuitry is programmed to: instructthe outlet actuator to maintain the second outlet damper at a 10% openposition during a first duration in aa bleed phase of the firstregeneration mode; and instruct the outlet actuator to maintain thesecond outlet damper at a 20% open position during a second duration inthe bleed phase after the first duration; instruct the outlet actuatorto maintain the second outlet damper at a 30% open position during athird duration in the bleed phase after the second duration; instructthe outlet actuator to maintain the second outlet damper at a 40% openposition during a fourth duration in the bleed phase after the thirdduration; and instruct the outlet actuator to maintain the second outletdamper at a 50% open position during a fifth duration in the bleed phaseafter the fourth duration.